diff --git a/Benchmarks/Sources/Generated/BridgeJS.ImportTS.swift b/Benchmarks/Sources/Generated/BridgeJS.ImportTS.swift
index 53f06222..871938cf 100644
--- a/Benchmarks/Sources/Generated/BridgeJS.ImportTS.swift
+++ b/Benchmarks/Sources/Generated/BridgeJS.ImportTS.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func benchmarkHelperNoop() -> Void {
+func benchmarkHelperNoop() throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Benchmarks", name: "bjs_benchmarkHelperNoop")
     func bjs_benchmarkHelperNoop() -> Void
@@ -16,9 +16,12 @@ func benchmarkHelperNoop() -> Void {
     }
     #endif
     bjs_benchmarkHelperNoop()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
 
-func benchmarkHelperNoopWithNumber(_ n: Double) -> Void {
+func benchmarkHelperNoopWithNumber(_ n: Double) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Benchmarks", name: "bjs_benchmarkHelperNoopWithNumber")
     func bjs_benchmarkHelperNoopWithNumber(_ n: Float64) -> Void
@@ -28,9 +31,12 @@ func benchmarkHelperNoopWithNumber(_ n: Double) -> Void {
     }
     #endif
     bjs_benchmarkHelperNoopWithNumber(n)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
 
-func benchmarkRunner(_ name: String, _ body: JSObject) -> Void {
+func benchmarkRunner(_ name: String, _ body: JSObject) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Benchmarks", name: "bjs_benchmarkRunner")
     func bjs_benchmarkRunner(_ name: Int32, _ body: Int32) -> Void
@@ -44,4 +50,7 @@ func benchmarkRunner(_ name: String, _ body: JSObject) -> Void {
         _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
     }
     bjs_benchmarkRunner(nameId, Int32(bitPattern: body.id))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
\ No newline at end of file
diff --git a/Examples/PlayBridgeJS/Package.swift b/Examples/PlayBridgeJS/Package.swift
index 76e95d1a..258518b4 100644
--- a/Examples/PlayBridgeJS/Package.swift
+++ b/Examples/PlayBridgeJS/Package.swift
@@ -22,6 +22,11 @@ let package = Package(
                 .product(name: "SwiftBasicFormat", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
             ],
+            exclude: [
+                "bridge-js.d.ts",
+                "bridge-js.config.json",
+                "Generated/JavaScript",
+            ],
             swiftSettings: [
                 .enableExperimentalFeature("Extern")
             ],
diff --git a/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ExportSwift.swift b/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ExportSwift.swift
index 283a3fbb..b0656df9 100644
--- a/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ExportSwift.swift
+++ b/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ExportSwift.swift
@@ -26,12 +26,12 @@ public func _bjs_PlayBridgeJS_update(_self: UnsafeMutableRawPointer, swiftSource
             _swift_js_init_memory(swiftSourceBytes, b.baseAddress.unsafelyUnwrapped)
             return Int(swiftSourceLen)
         }
-    let dtsSource = String(unsafeUninitializedCapacity: Int(dtsSourceLen)) { b in
+        let dtsSource = String(unsafeUninitializedCapacity: Int(dtsSourceLen)) { b in
             _swift_js_init_memory(dtsSourceBytes, b.baseAddress.unsafelyUnwrapped)
             return Int(dtsSourceLen)
         }
-    let ret = try Unmanaged<PlayBridgeJS>.fromOpaque(_self).takeUnretainedValue().update(swiftSource: swiftSource, dtsSource: dtsSource)
-    return Unmanaged.passRetained(ret).toOpaque()
+        let ret = try Unmanaged<PlayBridgeJS>.fromOpaque(_self).takeUnretainedValue().update(swiftSource: swiftSource, dtsSource: dtsSource)
+        return Unmanaged.passRetained(ret).toOpaque()
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
diff --git a/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ImportTS.swift b/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ImportTS.swift
index 6698cab5..5d82db08 100644
--- a/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ImportTS.swift
+++ b/Examples/PlayBridgeJS/Sources/PlayBridgeJS/Generated/BridgeJS.ImportTS.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func createTS2Skeleton() -> TS2Skeleton {
+func createTS2Skeleton() throws(JSException) -> TS2Skeleton {
     #if arch(wasm32)
     @_extern(wasm, module: "PlayBridgeJS", name: "bjs_createTS2Skeleton")
     func bjs_createTS2Skeleton() -> Int32
@@ -16,6 +16,9 @@ func createTS2Skeleton() -> TS2Skeleton {
     }
     #endif
     let ret = bjs_createTS2Skeleton()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return TS2Skeleton(takingThis: ret)
 }
 
@@ -30,7 +33,7 @@ struct TS2Skeleton {
         self.this = JSObject(id: UInt32(bitPattern: this))
     }
 
-    func convert(_ ts: String) -> String {
+    func convert(_ ts: String) throws(JSException) -> String {
         #if arch(wasm32)
         @_extern(wasm, module: "PlayBridgeJS", name: "bjs_TS2Skeleton_convert")
         func bjs_TS2Skeleton_convert(_ self: Int32, _ ts: Int32) -> Int32
@@ -44,6 +47,9 @@ struct TS2Skeleton {
             _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
         }
         let ret = bjs_TS2Skeleton_convert(Int32(bitPattern: self.this.id), tsId)
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         return String(unsafeUninitializedCapacity: Int(ret)) { b in
             _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
             return Int(ret)
diff --git a/Examples/PlayBridgeJS/Sources/PlayBridgeJS/main.swift b/Examples/PlayBridgeJS/Sources/PlayBridgeJS/main.swift
index 7dc5a57f..8f224994 100644
--- a/Examples/PlayBridgeJS/Sources/PlayBridgeJS/main.swift
+++ b/Examples/PlayBridgeJS/Sources/PlayBridgeJS/main.swift
@@ -9,6 +9,8 @@ import class Foundation.JSONDecoder
     @JS func update(swiftSource: String, dtsSource: String) throws(JSException) -> PlayBridgeJSOutput {
         do {
             return try _update(swiftSource: swiftSource, dtsSource: dtsSource)
+        } catch let error as JSException {
+            throw error
         } catch {
             throw JSException(message: String(describing: error))
         }
@@ -20,8 +22,8 @@ import class Foundation.JSONDecoder
         try exportSwift.addSourceFile(sourceFile, "Playground.swift")
         let exportResult = try exportSwift.finalize()
         var importTS = ImportTS(progress: .silent, moduleName: "Playground")
-        let ts2skeleton = createTS2Skeleton()
-        let skeletonJSONString = ts2skeleton.convert(dtsSource)
+        let ts2skeleton = try createTS2Skeleton()
+        let skeletonJSONString = try ts2skeleton.convert(dtsSource)
         let decoder = JSONDecoder()
         let importSkeleton = try decoder.decode(
             ImportedFileSkeleton.self,
diff --git a/Package.swift b/Package.swift
index f8b3b6e9..435ae1a1 100644
--- a/Package.swift
+++ b/Package.swift
@@ -151,12 +151,17 @@ let package = Package(
                 .product(name: "SwiftBasicFormat", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
             ],
-            path: "Plugins/BridgeJS/Sources/BridgeJSTool"
+            path: "Plugins/BridgeJS/Sources/BridgeJSTool",
+            exclude: ["TS2Skeleton/JavaScript"]
         ),
         .testTarget(
             name: "BridgeJSRuntimeTests",
             dependencies: ["JavaScriptKit"],
-            exclude: ["Generated/JavaScript"],
+            exclude: [
+                "bridge-js.config.json",
+                "bridge-js.d.ts",
+                "Generated/JavaScript",
+            ],
             swiftSettings: [
                 .enableExperimentalFeature("Extern")
             ]
diff --git a/Plugins/BridgeJS/Sources/BridgeJSCore/ExportSwift.swift b/Plugins/BridgeJS/Sources/BridgeJSCore/ExportSwift.swift
index 12960500..fefcf40c 100644
--- a/Plugins/BridgeJS/Sources/BridgeJSCore/ExportSwift.swift
+++ b/Plugins/BridgeJS/Sources/BridgeJSCore/ExportSwift.swift
@@ -56,7 +56,9 @@ class ExportSwift {
 
     fileprivate final class APICollector: SyntaxAnyVisitor {
         var exportedFunctions: [ExportedFunction] = []
-        var exportedClasses: [String: ExportedClass] = [:]
+        /// The names of the exported classes, in the order they were written in the source file
+        var exportedClassNames: [String] = []
+        var exportedClassByName: [String: ExportedClass] = [:]
         var errors: [DiagnosticError] = []
 
         enum State {
@@ -114,7 +116,7 @@ class ExportSwift {
                 return .skipChildren
             case .classBody(let name):
                 if let exportedFunction = visitFunction(node: node) {
-                    exportedClasses[name]?.methods.append(exportedFunction)
+                    exportedClassByName[name]?.methods.append(exportedFunction)
                 }
                 return .skipChildren
             }
@@ -217,7 +219,7 @@ class ExportSwift {
                 parameters: parameters,
                 effects: effects
             )
-            exportedClasses[name]?.constructor = constructor
+            exportedClassByName[name]?.constructor = constructor
             return .skipChildren
         }
 
@@ -226,11 +228,12 @@ class ExportSwift {
             stateStack.push(state: .classBody(name: name))
 
             guard node.attributes.hasJSAttribute() else { return .skipChildren }
-            exportedClasses[name] = ExportedClass(
+            exportedClassByName[name] = ExportedClass(
                 name: name,
                 constructor: nil,
                 methods: []
             )
+            exportedClassNames.append(name)
             return .visitChildren
         }
         override func visitPost(_ node: ClassDeclSyntax) {
@@ -242,7 +245,11 @@ class ExportSwift {
         let collector = APICollector(parent: self)
         collector.walk(sourceFile)
         exportedFunctions.append(contentsOf: collector.exportedFunctions)
-        exportedClasses.append(contentsOf: collector.exportedClasses.values)
+        exportedClasses.append(
+            contentsOf: collector.exportedClassNames.map {
+                collector.exportedClassByName[$0]!
+            }
+        )
         return collector.errors
     }
 
@@ -426,25 +433,7 @@ class ExportSwift {
         }
 
         func lowerReturnValue(returnType: BridgeType) {
-            switch returnType {
-            case .void:
-                abiReturnType = nil
-            case .bool:
-                abiReturnType = .i32
-            case .int:
-                abiReturnType = .i32
-            case .float:
-                abiReturnType = .f32
-            case .double:
-                abiReturnType = .f64
-            case .string:
-                abiReturnType = nil
-            case .jsObject:
-                abiReturnType = .i32
-            case .swiftHeapObject:
-                // UnsafeMutableRawPointer is returned as an i32 pointer
-                abiReturnType = .pointer
-            }
+            abiReturnType = returnType.abiReturnType
 
             switch returnType {
             case .void: break
diff --git a/Plugins/BridgeJS/Sources/BridgeJSCore/ImportTS.swift b/Plugins/BridgeJS/Sources/BridgeJSCore/ImportTS.swift
index 4aef01fd..37181114 100644
--- a/Plugins/BridgeJS/Sources/BridgeJSCore/ImportTS.swift
+++ b/Plugins/BridgeJS/Sources/BridgeJSCore/ImportTS.swift
@@ -151,6 +151,7 @@ struct ImportTS {
             } else {
                 body.append("let ret = \(raw: call)")
             }
+            body.append("if let error = _swift_js_take_exception() { throw error }")
         }
 
         func liftReturnValue(returnType: BridgeType) throws {
@@ -253,6 +254,7 @@ struct ImportTS {
                                 )
                             }
                         }),
+                        effectSpecifiers: ImportTS.buildFunctionEffect(throws: true, async: false),
                         returnClause: ReturnClauseSyntax(
                             arrow: .arrowToken(),
                             type: IdentifierTypeSyntax(name: .identifier(returnType.swiftType))
@@ -280,7 +282,8 @@ struct ImportTS {
                                     )
                                 }
                             }
-                        )
+                        ),
+                        effectSpecifiers: ImportTS.buildFunctionEffect(throws: true, async: false)
                     ),
                     bodyBuilder: {
                         self.renderImportDecl()
@@ -364,6 +367,7 @@ struct ImportTS {
             try builder.liftReturnValue(returnType: property.type)
             return AccessorDeclSyntax(
                 accessorSpecifier: .keyword(.get),
+                effectSpecifiers: Self.buildAccessorEffect(throws: true, async: false),
                 body: CodeBlockSyntax {
                     builder.renderImportDecl()
                     builder.body
@@ -371,31 +375,25 @@ struct ImportTS {
             )
         }
 
-        func renderSetterDecl(property: ImportedPropertySkeleton) throws -> AccessorDeclSyntax {
+        func renderSetterDecl(property: ImportedPropertySkeleton) throws -> DeclSyntax {
             let builder = ImportedThunkBuilder(
                 moduleName: moduleName,
                 abiName: property.setterAbiName(context: type)
             )
+            let newValue = Parameter(label: nil, name: "newValue", type: property.type)
             try builder.lowerParameter(param: Parameter(label: nil, name: "self", type: .jsObject(name)))
-            try builder.lowerParameter(param: Parameter(label: nil, name: "newValue", type: property.type))
+            try builder.lowerParameter(param: newValue)
             builder.call(returnType: .void)
-            return AccessorDeclSyntax(
-                modifier: DeclModifierSyntax(name: .keyword(.nonmutating)),
-                accessorSpecifier: .keyword(.set),
-                body: CodeBlockSyntax {
-                    builder.renderImportDecl()
-                    builder.body
-                }
+            return builder.renderThunkDecl(
+                name: "set\(property.name.capitalizedFirstLetter())",
+                parameters: [newValue],
+                returnType: .void
             )
         }
 
         func renderPropertyDecl(property: ImportedPropertySkeleton) throws -> [DeclSyntax] {
-            var accessorDecls: [AccessorDeclSyntax] = []
-            accessorDecls.append(try renderGetterDecl(property: property))
-            if !property.isReadonly {
-                accessorDecls.append(try renderSetterDecl(property: property))
-            }
-            return [
+            let accessorDecls: [AccessorDeclSyntax] = [try renderGetterDecl(property: property)]
+            var decls: [DeclSyntax] = [
                 DeclSyntax(
                     VariableDeclSyntax(
                         leadingTrivia: Self.renderDocumentation(documentation: property.documentation),
@@ -418,6 +416,10 @@ struct ImportTS {
                     )
                 )
             ]
+            if !property.isReadonly {
+                decls.append(try renderSetterDecl(property: property))
+            }
+            return decls
         }
         let classDecl = try StructDeclSyntax(
             leadingTrivia: Self.renderDocumentation(documentation: type.documentation),
@@ -469,4 +471,36 @@ struct ImportTS {
         let lines = documentation.split { $0.isNewline }
         return Trivia(pieces: lines.flatMap { [TriviaPiece.docLineComment("/// \($0)"), .newlines(1)] })
     }
+
+    static func buildFunctionEffect(throws: Bool, async: Bool) -> FunctionEffectSpecifiersSyntax {
+        return FunctionEffectSpecifiersSyntax(
+            asyncSpecifier: `async` ? .keyword(.async) : nil,
+            throwsClause: `throws`
+                ? ThrowsClauseSyntax(
+                    throwsSpecifier: .keyword(.throws),
+                    leftParen: .leftParenToken(),
+                    type: IdentifierTypeSyntax(name: .identifier("JSException")),
+                    rightParen: .rightParenToken()
+                ) : nil
+        )
+    }
+    static func buildAccessorEffect(throws: Bool, async: Bool) -> AccessorEffectSpecifiersSyntax {
+        return AccessorEffectSpecifiersSyntax(
+            asyncSpecifier: `async` ? .keyword(.async) : nil,
+            throwsClause: `throws`
+                ? ThrowsClauseSyntax(
+                    throwsSpecifier: .keyword(.throws),
+                    leftParen: .leftParenToken(),
+                    type: IdentifierTypeSyntax(name: .identifier("JSException")),
+                    rightParen: .rightParenToken()
+                ) : nil
+        )
+    }
+}
+
+extension String {
+    func capitalizedFirstLetter() -> String {
+        guard !isEmpty else { return self }
+        return prefix(1).uppercased() + dropFirst()
+    }
 }
diff --git a/Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift b/Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift
index 05a29aab..4d9ba596 100644
--- a/Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift
+++ b/Plugins/BridgeJS/Sources/BridgeJSLink/BridgeJSLink.swift
@@ -118,6 +118,7 @@ struct BridgeJSLink {
             export async function createInstantiator(options, swift) {
                 let instance;
                 let memory;
+                let setException;
                 const textDecoder = new TextDecoder("utf-8");
                 const textEncoder = new TextEncoder("utf-8");
 
@@ -161,6 +162,9 @@ struct BridgeJSLink {
                     setInstance: (i) => {
                         instance = i;
                         memory = instance.exports.memory;
+                        setException = (error) => {
+                            instance.exports._swift_js_exception.value = swift.memory.retain(error)
+                        }
                     },
                     /** @param {WebAssembly.Instance} instance */
                     createExports: (instance) => {
@@ -419,16 +423,24 @@ struct BridgeJSLink {
 
         func renderFunction(
             name: String,
-            returnExpr: String?
+            returnExpr: String?,
+            returnType: BridgeType
         ) -> [String] {
             var funcLines: [String] = []
             funcLines.append(
                 "function \(name)(\(parameterNames.joined(separator: ", "))) {"
             )
-            funcLines.append(contentsOf: bodyLines.map { $0.indent(count: 4) })
+            funcLines.append("try {".indent(count: 4))
+            funcLines.append(contentsOf: bodyLines.map { $0.indent(count: 8) })
             if let returnExpr = returnExpr {
-                funcLines.append("return \(returnExpr);".indent(count: 4))
+                funcLines.append("return \(returnExpr);".indent(count: 8))
             }
+            funcLines.append("} catch (error) {".indent(count: 4))
+            funcLines.append("setException(error);".indent(count: 8))
+            if let abiReturnType = returnType.abiReturnType {
+                funcLines.append("return \(abiReturnType.placeholderValue)".indent(count: 8))
+            }
+            funcLines.append("}".indent(count: 4))
             funcLines.append("}")
             return funcLines
         }
@@ -518,7 +530,8 @@ struct BridgeJSLink {
         let returnExpr = try thunkBuilder.lowerReturnValue(returnType: function.returnType)
         let funcLines = thunkBuilder.renderFunction(
             name: function.abiName(context: nil),
-            returnExpr: returnExpr
+            returnExpr: returnExpr,
+            returnType: function.returnType
         )
         importObjectBuilder.appendDts(
             [
@@ -591,7 +604,8 @@ struct BridgeJSLink {
         let abiName = constructor.abiName(context: type)
         let funcLines = thunkBuilder.renderFunction(
             name: abiName,
-            returnExpr: returnExpr
+            returnExpr: returnExpr,
+            returnType: returnType
         )
         importObjectBuilder.assignToImportObject(name: abiName, function: funcLines)
         importObjectBuilder.appendDts([
@@ -611,7 +625,8 @@ struct BridgeJSLink {
         let returnExpr = try emitCall(thunkBuilder)
         let funcLines = thunkBuilder.renderFunction(
             name: abiName,
-            returnExpr: returnExpr
+            returnExpr: returnExpr,
+            returnType: property.type
         )
         return (funcLines, [])
     }
@@ -629,7 +644,8 @@ struct BridgeJSLink {
         let returnExpr = try thunkBuilder.lowerReturnValue(returnType: method.returnType)
         let funcLines = thunkBuilder.renderFunction(
             name: method.abiName(context: context),
-            returnExpr: returnExpr
+            returnExpr: returnExpr,
+            returnType: method.returnType
         )
         return (funcLines, [])
     }
@@ -667,3 +683,11 @@ extension BridgeType {
         }
     }
 }
+
+extension WasmCoreType {
+    fileprivate var placeholderValue: String {
+        switch self {
+        case .i32, .i64, .f32, .f64, .pointer: return "0"
+        }
+    }
+}
diff --git a/Plugins/BridgeJS/Sources/BridgeJSSkeleton/BridgeJSSkeleton.swift b/Plugins/BridgeJS/Sources/BridgeJSSkeleton/BridgeJSSkeleton.swift
index 873849f9..5bfcc414 100644
--- a/Plugins/BridgeJS/Sources/BridgeJSSkeleton/BridgeJSSkeleton.swift
+++ b/Plugins/BridgeJS/Sources/BridgeJSSkeleton/BridgeJSSkeleton.swift
@@ -101,3 +101,20 @@ struct ImportedModuleSkeleton: Codable {
     let moduleName: String
     var children: [ImportedFileSkeleton]
 }
+
+extension BridgeType {
+    var abiReturnType: WasmCoreType? {
+        switch self {
+        case .void: return nil
+        case .bool: return .i32
+        case .int: return .i32
+        case .float: return .f32
+        case .double: return .f64
+        case .string: return nil
+        case .jsObject: return .i32
+        case .swiftHeapObject:
+            // UnsafeMutableRawPointer is returned as an i32 pointer
+            return .pointer
+        }
+    }
+}
diff --git a/Plugins/BridgeJS/Sources/BridgeJSTool/BridgeJSTool.swift b/Plugins/BridgeJS/Sources/BridgeJSTool/BridgeJSTool.swift
index 044bff0d..6096e2b3 100644
--- a/Plugins/BridgeJS/Sources/BridgeJSTool/BridgeJSTool.swift
+++ b/Plugins/BridgeJS/Sources/BridgeJSTool/BridgeJSTool.swift
@@ -159,7 +159,7 @@ import SwiftParser
             )
             let progress = ProgressReporting(verbose: doubleDashOptions["verbose"] == "true")
             let exporter = ExportSwift(progress: progress)
-            for inputFile in positionalArguments {
+            for inputFile in positionalArguments.sorted() {
                 let sourceURL = URL(fileURLWithPath: inputFile)
                 guard sourceURL.pathExtension == "swift" else { continue }
                 let sourceContent = try String(contentsOf: sourceURL, encoding: .utf8)
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/SnapshotTesting.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/SnapshotTesting.swift
index 28b34bf6..ce7066a6 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/SnapshotTesting.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/SnapshotTesting.swift
@@ -24,14 +24,15 @@ func assertSnapshot(
         let existingSnapshot = try String(contentsOf: snapshotPath, encoding: .utf8)
         let ok = existingSnapshot == String(data: input, encoding: .utf8)!
         let actualFilePath = snapshotPath.path + ".actual"
+        let updateSnapshots = ProcessInfo.processInfo.environment["UPDATE_SNAPSHOTS"] != nil
         func buildComment() -> Comment {
             "Snapshot mismatch: \(actualFilePath) \(snapshotPath.path)"
         }
-        if !ok {
-            try input.write(to: URL(fileURLWithPath: actualFilePath))
-        }
-        if ProcessInfo.processInfo.environment["UPDATE_SNAPSHOTS"] == nil {
+        if !updateSnapshots {
             #expect(ok, buildComment(), sourceLocation: sourceLocation)
+            if !ok {
+                try input.write(to: URL(fileURLWithPath: actualFilePath))
+            }
         } else {
             try input.write(to: snapshotPath)
         }
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/ArrayParameter.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/ArrayParameter.Import.js
index f619fcf2..c90b3919 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/ArrayParameter.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/ArrayParameter.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,18 +48,33 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_checkArray"] = function bjs_checkArray(a) {
-                options.imports.checkArray(swift.memory.getObject(a));
+                try {
+                    options.imports.checkArray(swift.memory.getObject(a));
+                } catch (error) {
+                    setException(error);
+                }
             }
             TestModule["bjs_checkArrayWithLength"] = function bjs_checkArrayWithLength(a, b) {
-                options.imports.checkArrayWithLength(swift.memory.getObject(a), b);
+                try {
+                    options.imports.checkArrayWithLength(swift.memory.getObject(a), b);
+                } catch (error) {
+                    setException(error);
+                }
             }
             TestModule["bjs_checkArray"] = function bjs_checkArray(a) {
-                options.imports.checkArray(swift.memory.getObject(a));
+                try {
+                    options.imports.checkArray(swift.memory.getObject(a));
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Interface.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Interface.Import.js
index fc6c3fcc..4d88bcdb 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Interface.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Interface.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,21 +48,39 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_returnAnimatable"] = function bjs_returnAnimatable() {
-                let ret = options.imports.returnAnimatable();
-                return swift.memory.retain(ret);
+                try {
+                    let ret = options.imports.returnAnimatable();
+                    return swift.memory.retain(ret);
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
             TestModule["bjs_Animatable_animate"] = function bjs_Animatable_animate(self, keyframes, options) {
-                let ret = swift.memory.getObject(self).animate(swift.memory.getObject(keyframes), swift.memory.getObject(options));
-                return swift.memory.retain(ret);
+                try {
+                    let ret = swift.memory.getObject(self).animate(swift.memory.getObject(keyframes), swift.memory.getObject(options));
+                    return swift.memory.retain(ret);
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
             TestModule["bjs_Animatable_getAnimations"] = function bjs_Animatable_getAnimations(self, options) {
-                let ret = swift.memory.getObject(self).getAnimations(swift.memory.getObject(options));
-                return swift.memory.retain(ret);
+                try {
+                    let ret = swift.memory.getObject(self).getAnimations(swift.memory.getObject(options));
+                    return swift.memory.retain(ret);
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Export.js
index 0d31689c..1f4d6cbc 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Import.js
index c8a58a3d..c6413b6b 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveParameters.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,12 +48,19 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_check"] = function bjs_check(a, b) {
-                options.imports.check(a, b);
+                try {
+                    options.imports.check(a, b);
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Export.js
index b2a16684..01dbcb74 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Import.js
index 690514e3..2a3292bc 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/PrimitiveReturn.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,17 +48,30 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_checkNumber"] = function bjs_checkNumber() {
-                let ret = options.imports.checkNumber();
-                return ret;
+                try {
+                    let ret = options.imports.checkNumber();
+                    return ret;
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
             TestModule["bjs_checkBoolean"] = function bjs_checkBoolean() {
-                let ret = options.imports.checkBoolean();
-                return ret !== 0;
+                try {
+                    let ret = options.imports.checkBoolean();
+                    return ret !== 0;
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Export.js
index ca37f7f5..7c2e883d 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Import.js
index 466b7786..c12e6c1e 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringParameter.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,19 +48,30 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_checkString"] = function bjs_checkString(a) {
-                const aObject = swift.memory.getObject(a);
-                swift.memory.release(a);
-                options.imports.checkString(aObject);
+                try {
+                    const aObject = swift.memory.getObject(a);
+                    swift.memory.release(a);
+                    options.imports.checkString(aObject);
+                } catch (error) {
+                    setException(error);
+                }
             }
             TestModule["bjs_checkStringWithLength"] = function bjs_checkStringWithLength(a, b) {
-                const aObject = swift.memory.getObject(a);
-                swift.memory.release(a);
-                options.imports.checkStringWithLength(aObject, b);
+                try {
+                    const aObject = swift.memory.getObject(a);
+                    swift.memory.release(a);
+                    options.imports.checkStringWithLength(aObject, b);
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Export.js
index d752e9e7..0362f3c4 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Import.js
index fb2ee18e..bb78c255 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/StringReturn.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,14 +48,21 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_checkString"] = function bjs_checkString() {
-                let ret = options.imports.checkString();
-                tmpRetBytes = textEncoder.encode(ret);
-                return tmpRetBytes.length;
+                try {
+                    let ret = options.imports.checkString();
+                    tmpRetBytes = textEncoder.encode(ret);
+                    return tmpRetBytes.length;
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/SwiftClass.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/SwiftClass.Export.js
index 58df1f25..7a5938a1 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/SwiftClass.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/SwiftClass.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Throws.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Throws.Export.js
index 6ebd05df..d0f9b623 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Throws.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/Throws.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeAlias.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeAlias.Import.js
index 41af7fa1..30639b4a 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeAlias.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeAlias.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,12 +48,19 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_checkSimple"] = function bjs_checkSimple(a) {
-                options.imports.checkSimple(a);
+                try {
+                    options.imports.checkSimple(a);
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeScriptClass.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeScriptClass.Import.js
index 52d36b77..f5cdc9ef 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeScriptClass.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/TypeScriptClass.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,39 +48,68 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_Greeter_init"] = function bjs_Greeter_init(name) {
-                const nameObject = swift.memory.getObject(name);
-                swift.memory.release(name);
-                let ret = new options.imports.Greeter(nameObject);
-                return swift.memory.retain(ret);
+                try {
+                    const nameObject = swift.memory.getObject(name);
+                    swift.memory.release(name);
+                    let ret = new options.imports.Greeter(nameObject);
+                    return swift.memory.retain(ret);
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
             TestModule["bjs_Greeter_name_get"] = function bjs_Greeter_name_get(self) {
-                let ret = swift.memory.getObject(self).name;
-                tmpRetBytes = textEncoder.encode(ret);
-                return tmpRetBytes.length;
+                try {
+                    let ret = swift.memory.getObject(self).name;
+                    tmpRetBytes = textEncoder.encode(ret);
+                    return tmpRetBytes.length;
+                } catch (error) {
+                    setException(error);
+                }
             }
             TestModule["bjs_Greeter_name_set"] = function bjs_Greeter_name_set(self, newValue) {
-                const newValueObject = swift.memory.getObject(newValue);
-                swift.memory.release(newValue);
-                swift.memory.getObject(self).name = newValueObject;
+                try {
+                    const newValueObject = swift.memory.getObject(newValue);
+                    swift.memory.release(newValue);
+                    swift.memory.getObject(self).name = newValueObject;
+                } catch (error) {
+                    setException(error);
+                }
             }
             TestModule["bjs_Greeter_age_get"] = function bjs_Greeter_age_get(self) {
-                let ret = swift.memory.getObject(self).age;
-                return ret;
+                try {
+                    let ret = swift.memory.getObject(self).age;
+                    return ret;
+                } catch (error) {
+                    setException(error);
+                    return 0
+                }
             }
             TestModule["bjs_Greeter_greet"] = function bjs_Greeter_greet(self) {
-                let ret = swift.memory.getObject(self).greet();
-                tmpRetBytes = textEncoder.encode(ret);
-                return tmpRetBytes.length;
+                try {
+                    let ret = swift.memory.getObject(self).greet();
+                    tmpRetBytes = textEncoder.encode(ret);
+                    return tmpRetBytes.length;
+                } catch (error) {
+                    setException(error);
+                }
             }
             TestModule["bjs_Greeter_changeName"] = function bjs_Greeter_changeName(self, name) {
-                const nameObject = swift.memory.getObject(name);
-                swift.memory.release(name);
-                swift.memory.getObject(self).changeName(nameObject);
+                try {
+                    const nameObject = swift.memory.getObject(name);
+                    swift.memory.release(name);
+                    swift.memory.getObject(self).changeName(nameObject);
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Export.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Export.js
index 29019e90..c7086eda 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Export.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Export.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -50,6 +51,9 @@ export async function createInstantiator(options, swift) {
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Import.js b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Import.js
index f57197b0..2482082c 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Import.js
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/BridgeJSLinkTests/VoidParameterVoidReturn.Import.js
@@ -7,6 +7,7 @@
 export async function createInstantiator(options, swift) {
     let instance;
     let memory;
+    let setException;
     const textDecoder = new TextDecoder("utf-8");
     const textEncoder = new TextEncoder("utf-8");
 
@@ -47,12 +48,19 @@ export async function createInstantiator(options, swift) {
             }
             const TestModule = importObject["TestModule"] = {};
             TestModule["bjs_check"] = function bjs_check() {
-                options.imports.check();
+                try {
+                    options.imports.check();
+                } catch (error) {
+                    setException(error);
+                }
             }
         },
         setInstance: (i) => {
             instance = i;
             memory = instance.exports.memory;
+            setException = (error) => {
+                instance.exports._swift_js_exception.value = swift.memory.retain(error)
+            }
         },
         /** @param {WebAssembly.Instance} instance */
         createExports: (instance) => {
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/ArrayParameter.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/ArrayParameter.swift
index 0a85c88f..34841ae8 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/ArrayParameter.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/ArrayParameter.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func checkArray(_ a: JSObject) -> Void {
+func checkArray(_ a: JSObject) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkArray")
     func bjs_checkArray(_ a: Int32) -> Void
@@ -16,9 +16,12 @@ func checkArray(_ a: JSObject) -> Void {
     }
     #endif
     bjs_checkArray(Int32(bitPattern: a.id))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
 
-func checkArrayWithLength(_ a: JSObject, _ b: Double) -> Void {
+func checkArrayWithLength(_ a: JSObject, _ b: Double) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkArrayWithLength")
     func bjs_checkArrayWithLength(_ a: Int32, _ b: Float64) -> Void
@@ -28,9 +31,12 @@ func checkArrayWithLength(_ a: JSObject, _ b: Double) -> Void {
     }
     #endif
     bjs_checkArrayWithLength(Int32(bitPattern: a.id), b)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
 
-func checkArray(_ a: JSObject) -> Void {
+func checkArray(_ a: JSObject) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkArray")
     func bjs_checkArray(_ a: Int32) -> Void
@@ -40,4 +46,7 @@ func checkArray(_ a: JSObject) -> Void {
     }
     #endif
     bjs_checkArray(Int32(bitPattern: a.id))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
\ No newline at end of file
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/Interface.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/Interface.swift
index 44fbb6ba..be9f524e 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/Interface.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/Interface.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func returnAnimatable() -> Animatable {
+func returnAnimatable() throws(JSException) -> Animatable {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_returnAnimatable")
     func bjs_returnAnimatable() -> Int32
@@ -16,6 +16,9 @@ func returnAnimatable() -> Animatable {
     }
     #endif
     let ret = bjs_returnAnimatable()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return Animatable(takingThis: ret)
 }
 
@@ -30,7 +33,7 @@ struct Animatable {
         self.this = JSObject(id: UInt32(bitPattern: this))
     }
 
-    func animate(_ keyframes: JSObject, _ options: JSObject) -> JSObject {
+    func animate(_ keyframes: JSObject, _ options: JSObject) throws(JSException) -> JSObject {
         #if arch(wasm32)
         @_extern(wasm, module: "Check", name: "bjs_Animatable_animate")
         func bjs_Animatable_animate(_ self: Int32, _ keyframes: Int32, _ options: Int32) -> Int32
@@ -40,10 +43,13 @@ struct Animatable {
         }
         #endif
         let ret = bjs_Animatable_animate(Int32(bitPattern: self.this.id), Int32(bitPattern: keyframes.id), Int32(bitPattern: options.id))
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         return JSObject(id: UInt32(bitPattern: ret))
     }
 
-    func getAnimations(_ options: JSObject) -> JSObject {
+    func getAnimations(_ options: JSObject) throws(JSException) -> JSObject {
         #if arch(wasm32)
         @_extern(wasm, module: "Check", name: "bjs_Animatable_getAnimations")
         func bjs_Animatable_getAnimations(_ self: Int32, _ options: Int32) -> Int32
@@ -53,6 +59,9 @@ struct Animatable {
         }
         #endif
         let ret = bjs_Animatable_getAnimations(Int32(bitPattern: self.this.id), Int32(bitPattern: options.id))
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         return JSObject(id: UInt32(bitPattern: ret))
     }
 
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveParameters.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveParameters.swift
index c5d23884..c47f5f40 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveParameters.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveParameters.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func check(_ a: Double, _ b: Bool) -> Void {
+func check(_ a: Double, _ b: Bool) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_check")
     func bjs_check(_ a: Float64, _ b: Int32) -> Void
@@ -16,4 +16,7 @@ func check(_ a: Double, _ b: Bool) -> Void {
     }
     #endif
     bjs_check(a, Int32(b ? 1 : 0))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
\ No newline at end of file
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveReturn.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveReturn.swift
index df1a469a..cf26a52f 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveReturn.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/PrimitiveReturn.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func checkNumber() -> Double {
+func checkNumber() throws(JSException) -> Double {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkNumber")
     func bjs_checkNumber() -> Float64
@@ -16,10 +16,13 @@ func checkNumber() -> Double {
     }
     #endif
     let ret = bjs_checkNumber()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return Double(ret)
 }
 
-func checkBoolean() -> Bool {
+func checkBoolean() throws(JSException) -> Bool {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkBoolean")
     func bjs_checkBoolean() -> Int32
@@ -29,5 +32,8 @@ func checkBoolean() -> Bool {
     }
     #endif
     let ret = bjs_checkBoolean()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return ret == 1
 }
\ No newline at end of file
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringParameter.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringParameter.swift
index 8cac3ce6..aabffacc 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringParameter.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringParameter.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func checkString(_ a: String) -> Void {
+func checkString(_ a: String) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkString")
     func bjs_checkString(_ a: Int32) -> Void
@@ -20,9 +20,12 @@ func checkString(_ a: String) -> Void {
         _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
     }
     bjs_checkString(aId)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
 
-func checkStringWithLength(_ a: String, _ b: Double) -> Void {
+func checkStringWithLength(_ a: String, _ b: Double) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkStringWithLength")
     func bjs_checkStringWithLength(_ a: Int32, _ b: Float64) -> Void
@@ -36,4 +39,7 @@ func checkStringWithLength(_ a: String, _ b: Double) -> Void {
         _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
     }
     bjs_checkStringWithLength(aId, b)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
\ No newline at end of file
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringReturn.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringReturn.swift
index 282476b0..af7b5162 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringReturn.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/StringReturn.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func checkString() -> String {
+func checkString() throws(JSException) -> String {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkString")
     func bjs_checkString() -> Int32
@@ -16,6 +16,9 @@ func checkString() -> String {
     }
     #endif
     let ret = bjs_checkString()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return String(unsafeUninitializedCapacity: Int(ret)) { b in
         _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
         return Int(ret)
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeAlias.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeAlias.swift
index 7eeefcc7..7523101f 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeAlias.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeAlias.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func checkSimple(_ a: Double) -> Void {
+func checkSimple(_ a: Double) throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_checkSimple")
     func bjs_checkSimple(_ a: Float64) -> Void
@@ -16,4 +16,7 @@ func checkSimple(_ a: Double) -> Void {
     }
     #endif
     bjs_checkSimple(a)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
\ No newline at end of file
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeScriptClass.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeScriptClass.swift
index 39b6a85c..7a1f2a2c 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeScriptClass.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/TypeScriptClass.swift
@@ -17,7 +17,7 @@ struct Greeter {
         self.this = JSObject(id: UInt32(bitPattern: this))
     }
 
-    init(_ name: String) {
+    init(_ name: String) throws(JSException) {
         #if arch(wasm32)
         @_extern(wasm, module: "Check", name: "bjs_Greeter_init")
         func bjs_Greeter_init(_ name: Int32) -> Int32
@@ -31,11 +31,14 @@ struct Greeter {
             _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
         }
         let ret = bjs_Greeter_init(nameId)
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         self.this = JSObject(id: UInt32(bitPattern: ret))
     }
 
     var name: String {
-        get {
+        get throws(JSException) {
             #if arch(wasm32)
             @_extern(wasm, module: "Check", name: "bjs_Greeter_name_get")
             func bjs_Greeter_name_get(_ self: Int32) -> Int32
@@ -45,30 +48,37 @@ struct Greeter {
             }
             #endif
             let ret = bjs_Greeter_name_get(Int32(bitPattern: self.this.id))
+            if let error = _swift_js_take_exception() {
+                throw error
+            }
             return String(unsafeUninitializedCapacity: Int(ret)) { b in
                 _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
                 return Int(ret)
             }
         }
-        nonmutating set {
-            #if arch(wasm32)
-            @_extern(wasm, module: "Check", name: "bjs_Greeter_name_set")
-            func bjs_Greeter_name_set(_ self: Int32, _ newValue: Int32) -> Void
-            #else
-            func bjs_Greeter_name_set(_ self: Int32, _ newValue: Int32) -> Void {
-                fatalError("Only available on WebAssembly")
-            }
-            #endif
-            var newValue = newValue
-            let newValueId = newValue.withUTF8 { b in
-                _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
-            }
-            bjs_Greeter_name_set(Int32(bitPattern: self.this.id), newValueId)
+    }
+
+    func setName(_ newValue: String) throws(JSException) -> Void {
+        #if arch(wasm32)
+        @_extern(wasm, module: "Check", name: "bjs_Greeter_name_set")
+        func bjs_Greeter_name_set(_ self: Int32, _ newValue: Int32) -> Void
+        #else
+        func bjs_Greeter_name_set(_ self: Int32, _ newValue: Int32) -> Void {
+            fatalError("Only available on WebAssembly")
+        }
+        #endif
+        var newValue = newValue
+        let newValueId = newValue.withUTF8 { b in
+            _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
+        }
+        bjs_Greeter_name_set(Int32(bitPattern: self.this.id), newValueId)
+        if let error = _swift_js_take_exception() {
+            throw error
         }
     }
 
     var age: Double {
-        get {
+        get throws(JSException) {
             #if arch(wasm32)
             @_extern(wasm, module: "Check", name: "bjs_Greeter_age_get")
             func bjs_Greeter_age_get(_ self: Int32) -> Float64
@@ -78,11 +88,14 @@ struct Greeter {
             }
             #endif
             let ret = bjs_Greeter_age_get(Int32(bitPattern: self.this.id))
+            if let error = _swift_js_take_exception() {
+                throw error
+            }
             return Double(ret)
         }
     }
 
-    func greet() -> String {
+    func greet() throws(JSException) -> String {
         #if arch(wasm32)
         @_extern(wasm, module: "Check", name: "bjs_Greeter_greet")
         func bjs_Greeter_greet(_ self: Int32) -> Int32
@@ -92,13 +105,16 @@ struct Greeter {
         }
         #endif
         let ret = bjs_Greeter_greet(Int32(bitPattern: self.this.id))
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         return String(unsafeUninitializedCapacity: Int(ret)) { b in
             _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
             return Int(ret)
         }
     }
 
-    func changeName(_ name: String) -> Void {
+    func changeName(_ name: String) throws(JSException) -> Void {
         #if arch(wasm32)
         @_extern(wasm, module: "Check", name: "bjs_Greeter_changeName")
         func bjs_Greeter_changeName(_ self: Int32, _ name: Int32) -> Void
@@ -112,6 +128,9 @@ struct Greeter {
             _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
         }
         bjs_Greeter_changeName(Int32(bitPattern: self.this.id), nameId)
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
     }
 
 }
\ No newline at end of file
diff --git a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/VoidParameterVoidReturn.swift b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/VoidParameterVoidReturn.swift
index eccd1728..ae7ae0e8 100644
--- a/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/VoidParameterVoidReturn.swift
+++ b/Plugins/BridgeJS/Tests/BridgeJSToolTests/__Snapshots__/ImportTSTests/VoidParameterVoidReturn.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func check() -> Void {
+func check() throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "Check", name: "bjs_check")
     func bjs_check() -> Void
@@ -16,4 +16,7 @@ func check() -> Void {
     }
     #endif
     bjs_check()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
\ No newline at end of file
diff --git a/Plugins/PackageToJS/Templates/runtime.mjs b/Plugins/PackageToJS/Templates/runtime.mjs
index 66a2e0ad..447f2090 100644
--- a/Plugins/PackageToJS/Templates/runtime.mjs
+++ b/Plugins/PackageToJS/Templates/runtime.mjs
@@ -242,11 +242,11 @@ else if (typeof self !== "undefined") {
 class JSObjectSpace {
     constructor() {
         this._heapValueById = new Map();
-        this._heapValueById.set(0, globalVariable);
+        this._heapValueById.set(1, globalVariable);
         this._heapEntryByValue = new Map();
-        this._heapEntryByValue.set(globalVariable, { id: 0, rc: 1 });
-        // Note: 0 is preserved for global
-        this._heapNextKey = 1;
+        this._heapEntryByValue.set(globalVariable, { id: 1, rc: 1 });
+        // Note: 0 is preserved for invalid references, 1 is preserved for globalThis
+        this._heapNextKey = 2;
     }
     retain(value) {
         const entry = this._heapEntryByValue.get(value);
diff --git a/Runtime/src/object-heap.ts b/Runtime/src/object-heap.ts
index ecc2d218..b90fc4ef 100644
--- a/Runtime/src/object-heap.ts
+++ b/Runtime/src/object-heap.ts
@@ -12,13 +12,13 @@ export class JSObjectSpace {
 
     constructor() {
         this._heapValueById = new Map();
-        this._heapValueById.set(0, globalVariable);
+        this._heapValueById.set(1, globalVariable);
 
         this._heapEntryByValue = new Map();
-        this._heapEntryByValue.set(globalVariable, { id: 0, rc: 1 });
+        this._heapEntryByValue.set(globalVariable, { id: 1, rc: 1 });
 
-        // Note: 0 is preserved for global
-        this._heapNextKey = 1;
+        // Note: 0 is preserved for invalid references, 1 is preserved for globalThis
+        this._heapNextKey = 2;
     }
 
     retain(value: any) {
diff --git a/Sources/JavaScriptKit/BridgeJSInstrincics.swift b/Sources/JavaScriptKit/BridgeJSInstrincics.swift
index e2c54026..1a8bad7f 100644
--- a/Sources/JavaScriptKit/BridgeJSInstrincics.swift
+++ b/Sources/JavaScriptKit/BridgeJSInstrincics.swift
@@ -1,5 +1,7 @@
+import _CJavaScriptKit
+
 #if !arch(wasm32)
-private func _onlyAvailableOnWasm() -> Never {
+@usableFromInline func _onlyAvailableOnWasm() -> Never {
     fatalError("Only available on WebAssembly")
 }
 #endif
@@ -57,3 +59,16 @@ private func _onlyAvailableOnWasm() -> Never {
     _onlyAvailableOnWasm()
 }
 #endif
+
+@_spi(BridgeJS) @_transparent public func _swift_js_take_exception() -> JSException? {
+    #if arch(wasm32)
+    let value = _swift_js_exception_get()
+    if _fastPath(value == 0) {
+        return nil
+    }
+    _swift_js_exception_set(0)
+    return JSException(JSObject(id: UInt32(bitPattern: value)).jsValue)
+    #else
+    _onlyAvailableOnWasm()
+    #endif
+}
diff --git a/Sources/JavaScriptKit/FundamentalObjects/JSObject.swift b/Sources/JavaScriptKit/FundamentalObjects/JSObject.swift
index 8892e987..b9330ae8 100644
--- a/Sources/JavaScriptKit/FundamentalObjects/JSObject.swift
+++ b/Sources/JavaScriptKit/FundamentalObjects/JSObject.swift
@@ -218,7 +218,7 @@ public class JSObject: Equatable, ExpressibleByDictionaryLiteral {
         return swjs_instanceof(id, constructor.id)
     }
 
-    static let _JS_Predef_Value_Global: JavaScriptObjectRef = 0
+    static let _JS_Predef_Value_Global: JavaScriptObjectRef = 1
 
     /// A `JSObject` of the global scope object.
     /// This allows access to the global properties and global names by accessing the `JSObject` returned.
diff --git a/Sources/JavaScriptKit/JSException.swift b/Sources/JavaScriptKit/JSException.swift
index 714b83aa..4d95e207 100644
--- a/Sources/JavaScriptKit/JSException.swift
+++ b/Sources/JavaScriptKit/JSException.swift
@@ -34,6 +34,7 @@ public struct JSException: Error, Equatable, CustomStringConvertible {
     /// Initializes a new JSException instance with a value thrown from JavaScript.
     ///
     /// Only available within the package. This must be called on the thread where the exception object created.
+    @usableFromInline
     package init(_ thrownValue: JSValue) {
         self._thrownValue = thrownValue
         // Capture the stringified representation on the object owner thread
diff --git a/Sources/_CJavaScriptKit/_CJavaScriptKit.c b/Sources/_CJavaScriptKit/_CJavaScriptKit.c
index a3288180..9df18b88 100644
--- a/Sources/_CJavaScriptKit/_CJavaScriptKit.c
+++ b/Sources/_CJavaScriptKit/_CJavaScriptKit.c
@@ -1,4 +1,6 @@
+#include <stdint.h>
 #include "_CJavaScriptKit.h"
+#include "WasmGlobalMacros.h"
 #if __wasm32__
 # ifndef __wasi__
 # if __has_include("malloc.h")
@@ -60,6 +62,9 @@ int swjs_library_features(void) {
     return _library_features();
 }
 # endif
+
+WASM_GLOBAL_DEFINE_STORAGE(_swift_js_exception, i32)
+WASM_EXPORT_NAME(_swift_js_exception, _swift_js_exception)
 #endif
 
 int swjs_get_worker_thread_id_cached(void) {
diff --git a/Sources/_CJavaScriptKit/include/BridgeJSInstrincics.h b/Sources/_CJavaScriptKit/include/BridgeJSInstrincics.h
new file mode 100644
index 00000000..4f5ba93c
--- /dev/null
+++ b/Sources/_CJavaScriptKit/include/BridgeJSInstrincics.h
@@ -0,0 +1,11 @@
+#ifndef _CJavaScriptKit_BridgeJSInstrincics_h
+#define _CJavaScriptKit_BridgeJSInstrincics_h
+
+#include <stdint.h>
+#include "WasmGlobalMacros.h"
+
+#if __wasm__
+WASM_GLOBAL_DEFINE_INLINE_ACCESSORS(_swift_js_exception, i32, int32_t)
+#endif
+
+#endif
diff --git a/Sources/_CJavaScriptKit/include/WasmGlobalMacros.h b/Sources/_CJavaScriptKit/include/WasmGlobalMacros.h
new file mode 100644
index 00000000..5e7aeb97
--- /dev/null
+++ b/Sources/_CJavaScriptKit/include/WasmGlobalMacros.h
@@ -0,0 +1,45 @@
+#ifndef _CJavaScriptKit_WasmGlobalMacros_h
+#define _CJavaScriptKit_WasmGlobalMacros_h
+
+// Define an inline getter for a Wasm global
+#define WASM_GLOBAL_DEFINE_INLINE_GETTER(name, core_type, c_type) \
+    static inline c_type name##_get(void) { \
+        c_type val; \
+        __asm__( \
+            ".globaltype " #name ", " #core_type "\n" \
+            "global.get " #name "\n" \
+            "local.set %0\n" \
+            : "=r"(val)); \
+        return val; \
+    }
+
+// Define an inline setter for a Wasm global
+#define WASM_GLOBAL_DEFINE_INLINE_SETTER(name, core_type, c_type) \
+    static inline void name##_set(c_type val) { \
+        __asm__( \
+            ".globaltype " #name ", " #core_type "\n" \
+            "local.get %0\n" \
+            "global.set " #name "\n" \
+            : : "r"(val)); \
+    }
+
+// Define an inline getter and setter for a Wasm global
+#define WASM_GLOBAL_DEFINE_INLINE_ACCESSORS(name, core_type, c_type) \
+    WASM_GLOBAL_DEFINE_INLINE_GETTER(name, core_type, c_type) \
+    WASM_GLOBAL_DEFINE_INLINE_SETTER(name, core_type, c_type)
+
+// Define a Wasm global storage
+#define WASM_GLOBAL_DEFINE_STORAGE(name, core_type) \
+    __asm__( \
+        ".globaltype " #name ", " #core_type "\n" \
+        ".global " #name "\n" \
+        #name ":\n" \
+    );
+
+// Define an export name for a Wasm value
+#define WASM_EXPORT_NAME(name, export_name) \
+    __asm__( \
+        ".export_name " #name ", " #export_name "\n" \
+    );
+
+#endif
diff --git a/Sources/_CJavaScriptKit/include/module.modulemap b/Sources/_CJavaScriptKit/include/module.modulemap
index 8f4b6926..3afe1283 100644
--- a/Sources/_CJavaScriptKit/include/module.modulemap
+++ b/Sources/_CJavaScriptKit/include/module.modulemap
@@ -1,4 +1,5 @@
 module _CJavaScriptKit {
     header "_CJavaScriptKit.h"
+    header "BridgeJSInstrincics.h"
     export *
 }
diff --git a/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ExportSwift.swift b/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ExportSwift.swift
index 6c11869f..2a91da9f 100644
--- a/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ExportSwift.swift
+++ b/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ExportSwift.swift
@@ -129,7 +129,7 @@ public func _bjs_throwsWithIntResult() -> Int32 {
     #if arch(wasm32)
     do {
         let ret = try throwsWithIntResult()
-    return Int32(ret)
+        return Int32(ret)
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
@@ -154,7 +154,7 @@ public func _bjs_throwsWithStringResult() -> Void {
     #if arch(wasm32)
     do {
         var ret = try throwsWithStringResult()
-    return ret.withUTF8 { ptr in
+        return ret.withUTF8 { ptr in
             _swift_js_return_string(ptr.baseAddress, Int32(ptr.count))
         }
     } catch let error {
@@ -181,7 +181,7 @@ public func _bjs_throwsWithBoolResult() -> Int32 {
     #if arch(wasm32)
     do {
         let ret = try throwsWithBoolResult()
-    return Int32(ret ? 1 : 0)
+        return Int32(ret ? 1 : 0)
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
@@ -206,7 +206,7 @@ public func _bjs_throwsWithFloatResult() -> Float32 {
     #if arch(wasm32)
     do {
         let ret = try throwsWithFloatResult()
-    return Float32(ret)
+        return Float32(ret)
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
@@ -231,7 +231,7 @@ public func _bjs_throwsWithDoubleResult() -> Float64 {
     #if arch(wasm32)
     do {
         let ret = try throwsWithDoubleResult()
-    return Float64(ret)
+        return Float64(ret)
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
@@ -256,7 +256,7 @@ public func _bjs_throwsWithSwiftHeapObjectResult() -> UnsafeMutableRawPointer {
     #if arch(wasm32)
     do {
         let ret = try throwsWithSwiftHeapObjectResult()
-    return Unmanaged.passRetained(ret).toOpaque()
+        return Unmanaged.passRetained(ret).toOpaque()
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
@@ -281,7 +281,7 @@ public func _bjs_throwsWithJSObjectResult() -> Int32 {
     #if arch(wasm32)
     do {
         let ret = try throwsWithJSObjectResult()
-    return _swift_js_retain(Int32(bitPattern: ret.id))
+        return _swift_js_retain(Int32(bitPattern: ret.id))
     } catch let error {
         if let error = error.thrownValue.object {
             withExtendedLifetime(error) {
diff --git a/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ImportTS.swift b/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ImportTS.swift
index 95150e0e..fd558ab8 100644
--- a/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ImportTS.swift
+++ b/Tests/BridgeJSRuntimeTests/Generated/BridgeJS.ImportTS.swift
@@ -6,7 +6,7 @@
 
 @_spi(BridgeJS) import JavaScriptKit
 
-func jsRoundTripVoid() -> Void {
+func jsRoundTripVoid() throws(JSException) -> Void {
     #if arch(wasm32)
     @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsRoundTripVoid")
     func bjs_jsRoundTripVoid() -> Void
@@ -16,9 +16,12 @@ func jsRoundTripVoid() -> Void {
     }
     #endif
     bjs_jsRoundTripVoid()
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
 }
 
-func jsRoundTripNumber(_ v: Double) -> Double {
+func jsRoundTripNumber(_ v: Double) throws(JSException) -> Double {
     #if arch(wasm32)
     @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsRoundTripNumber")
     func bjs_jsRoundTripNumber(_ v: Float64) -> Float64
@@ -28,10 +31,13 @@ func jsRoundTripNumber(_ v: Double) -> Double {
     }
     #endif
     let ret = bjs_jsRoundTripNumber(v)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return Double(ret)
 }
 
-func jsRoundTripBool(_ v: Bool) -> Bool {
+func jsRoundTripBool(_ v: Bool) throws(JSException) -> Bool {
     #if arch(wasm32)
     @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsRoundTripBool")
     func bjs_jsRoundTripBool(_ v: Int32) -> Int32
@@ -41,10 +47,13 @@ func jsRoundTripBool(_ v: Bool) -> Bool {
     }
     #endif
     let ret = bjs_jsRoundTripBool(Int32(v ? 1 : 0))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return ret == 1
 }
 
-func jsRoundTripString(_ v: String) -> String {
+func jsRoundTripString(_ v: String) throws(JSException) -> String {
     #if arch(wasm32)
     @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsRoundTripString")
     func bjs_jsRoundTripString(_ v: Int32) -> Int32
@@ -58,6 +67,75 @@ func jsRoundTripString(_ v: String) -> String {
         _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
     }
     let ret = bjs_jsRoundTripString(vId)
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
+    return String(unsafeUninitializedCapacity: Int(ret)) { b in
+        _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
+        return Int(ret)
+    }
+}
+
+func jsThrowOrVoid(_ shouldThrow: Bool) throws(JSException) -> Void {
+    #if arch(wasm32)
+    @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsThrowOrVoid")
+    func bjs_jsThrowOrVoid(_ shouldThrow: Int32) -> Void
+    #else
+    func bjs_jsThrowOrVoid(_ shouldThrow: Int32) -> Void {
+        fatalError("Only available on WebAssembly")
+    }
+    #endif
+    bjs_jsThrowOrVoid(Int32(shouldThrow ? 1 : 0))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
+}
+
+func jsThrowOrNumber(_ shouldThrow: Bool) throws(JSException) -> Double {
+    #if arch(wasm32)
+    @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsThrowOrNumber")
+    func bjs_jsThrowOrNumber(_ shouldThrow: Int32) -> Float64
+    #else
+    func bjs_jsThrowOrNumber(_ shouldThrow: Int32) -> Float64 {
+        fatalError("Only available on WebAssembly")
+    }
+    #endif
+    let ret = bjs_jsThrowOrNumber(Int32(shouldThrow ? 1 : 0))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
+    return Double(ret)
+}
+
+func jsThrowOrBool(_ shouldThrow: Bool) throws(JSException) -> Bool {
+    #if arch(wasm32)
+    @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsThrowOrBool")
+    func bjs_jsThrowOrBool(_ shouldThrow: Int32) -> Int32
+    #else
+    func bjs_jsThrowOrBool(_ shouldThrow: Int32) -> Int32 {
+        fatalError("Only available on WebAssembly")
+    }
+    #endif
+    let ret = bjs_jsThrowOrBool(Int32(shouldThrow ? 1 : 0))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
+    return ret == 1
+}
+
+func jsThrowOrString(_ shouldThrow: Bool) throws(JSException) -> String {
+    #if arch(wasm32)
+    @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_jsThrowOrString")
+    func bjs_jsThrowOrString(_ shouldThrow: Int32) -> Int32
+    #else
+    func bjs_jsThrowOrString(_ shouldThrow: Int32) -> Int32 {
+        fatalError("Only available on WebAssembly")
+    }
+    #endif
+    let ret = bjs_jsThrowOrString(Int32(shouldThrow ? 1 : 0))
+    if let error = _swift_js_take_exception() {
+        throw error
+    }
     return String(unsafeUninitializedCapacity: Int(ret)) { b in
         _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
         return Int(ret)
@@ -75,7 +153,7 @@ struct JsGreeter {
         self.this = JSObject(id: UInt32(bitPattern: this))
     }
 
-    init(_ name: String, _ prefix: String) {
+    init(_ name: String, _ prefix: String) throws(JSException) {
         #if arch(wasm32)
         @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_init")
         func bjs_JsGreeter_init(_ name: Int32, _ prefix: Int32) -> Int32
@@ -93,11 +171,14 @@ struct JsGreeter {
             _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
         }
         let ret = bjs_JsGreeter_init(nameId, prefixId)
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         self.this = JSObject(id: UInt32(bitPattern: ret))
     }
 
     var name: String {
-        get {
+        get throws(JSException) {
             #if arch(wasm32)
             @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_name_get")
             func bjs_JsGreeter_name_get(_ self: Int32) -> Int32
@@ -107,30 +188,37 @@ struct JsGreeter {
             }
             #endif
             let ret = bjs_JsGreeter_name_get(Int32(bitPattern: self.this.id))
+            if let error = _swift_js_take_exception() {
+                throw error
+            }
             return String(unsafeUninitializedCapacity: Int(ret)) { b in
                 _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
                 return Int(ret)
             }
         }
-        nonmutating set {
-            #if arch(wasm32)
-            @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_name_set")
-            func bjs_JsGreeter_name_set(_ self: Int32, _ newValue: Int32) -> Void
-            #else
-            func bjs_JsGreeter_name_set(_ self: Int32, _ newValue: Int32) -> Void {
-                fatalError("Only available on WebAssembly")
-            }
-            #endif
-            var newValue = newValue
-            let newValueId = newValue.withUTF8 { b in
-                _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
-            }
-            bjs_JsGreeter_name_set(Int32(bitPattern: self.this.id), newValueId)
+    }
+
+    func setName(_ newValue: String) throws(JSException) -> Void {
+        #if arch(wasm32)
+        @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_name_set")
+        func bjs_JsGreeter_name_set(_ self: Int32, _ newValue: Int32) -> Void
+        #else
+        func bjs_JsGreeter_name_set(_ self: Int32, _ newValue: Int32) -> Void {
+            fatalError("Only available on WebAssembly")
+        }
+        #endif
+        var newValue = newValue
+        let newValueId = newValue.withUTF8 { b in
+            _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
+        }
+        bjs_JsGreeter_name_set(Int32(bitPattern: self.this.id), newValueId)
+        if let error = _swift_js_take_exception() {
+            throw error
         }
     }
 
     var prefix: String {
-        get {
+        get throws(JSException) {
             #if arch(wasm32)
             @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_prefix_get")
             func bjs_JsGreeter_prefix_get(_ self: Int32) -> Int32
@@ -140,6 +228,9 @@ struct JsGreeter {
             }
             #endif
             let ret = bjs_JsGreeter_prefix_get(Int32(bitPattern: self.this.id))
+            if let error = _swift_js_take_exception() {
+                throw error
+            }
             return String(unsafeUninitializedCapacity: Int(ret)) { b in
                 _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
                 return Int(ret)
@@ -147,7 +238,7 @@ struct JsGreeter {
         }
     }
 
-    func greet() -> String {
+    func greet() throws(JSException) -> String {
         #if arch(wasm32)
         @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_greet")
         func bjs_JsGreeter_greet(_ self: Int32) -> Int32
@@ -157,13 +248,16 @@ struct JsGreeter {
         }
         #endif
         let ret = bjs_JsGreeter_greet(Int32(bitPattern: self.this.id))
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
         return String(unsafeUninitializedCapacity: Int(ret)) { b in
             _swift_js_init_memory_with_result(b.baseAddress.unsafelyUnwrapped, Int32(ret))
             return Int(ret)
         }
     }
 
-    func changeName(_ name: String) -> Void {
+    func changeName(_ name: String) throws(JSException) -> Void {
         #if arch(wasm32)
         @_extern(wasm, module: "BridgeJSRuntimeTests", name: "bjs_JsGreeter_changeName")
         func bjs_JsGreeter_changeName(_ self: Int32, _ name: Int32) -> Void
@@ -177,6 +271,9 @@ struct JsGreeter {
             _swift_js_make_js_string(b.baseAddress.unsafelyUnwrapped, Int32(b.count))
         }
         bjs_JsGreeter_changeName(Int32(bitPattern: self.this.id), nameId)
+        if let error = _swift_js_take_exception() {
+            throw error
+        }
     }
 
 }
\ No newline at end of file
diff --git a/Tests/BridgeJSRuntimeTests/Generated/JavaScript/BridgeJS.ImportTS.json b/Tests/BridgeJSRuntimeTests/Generated/JavaScript/BridgeJS.ImportTS.json
index ad8fcd87..bf3190b8 100644
--- a/Tests/BridgeJSRuntimeTests/Generated/JavaScript/BridgeJS.ImportTS.json
+++ b/Tests/BridgeJSRuntimeTests/Generated/JavaScript/BridgeJS.ImportTS.json
@@ -64,6 +64,78 @@
           "returnType" : {
             "string" : {
 
+            }
+          }
+        },
+        {
+          "name" : "jsThrowOrVoid",
+          "parameters" : [
+            {
+              "name" : "shouldThrow",
+              "type" : {
+                "bool" : {
+
+                }
+              }
+            }
+          ],
+          "returnType" : {
+            "void" : {
+
+            }
+          }
+        },
+        {
+          "name" : "jsThrowOrNumber",
+          "parameters" : [
+            {
+              "name" : "shouldThrow",
+              "type" : {
+                "bool" : {
+
+                }
+              }
+            }
+          ],
+          "returnType" : {
+            "double" : {
+
+            }
+          }
+        },
+        {
+          "name" : "jsThrowOrBool",
+          "parameters" : [
+            {
+              "name" : "shouldThrow",
+              "type" : {
+                "bool" : {
+
+                }
+              }
+            }
+          ],
+          "returnType" : {
+            "bool" : {
+
+            }
+          }
+        },
+        {
+          "name" : "jsThrowOrString",
+          "parameters" : [
+            {
+              "name" : "shouldThrow",
+              "type" : {
+                "bool" : {
+
+                }
+              }
+            }
+          ],
+          "returnType" : {
+            "string" : {
+
             }
           }
         }
diff --git a/Tests/BridgeJSRuntimeTests/ImportAPITests.swift b/Tests/BridgeJSRuntimeTests/ImportAPITests.swift
index a8d586bf..f0112ed1 100644
--- a/Tests/BridgeJSRuntimeTests/ImportAPITests.swift
+++ b/Tests/BridgeJSRuntimeTests/ImportAPITests.swift
@@ -2,11 +2,11 @@ import XCTest
 import JavaScriptKit
 
 class ImportAPITests: XCTestCase {
-    func testRoundTripVoid() {
-        jsRoundTripVoid()
+    func testRoundTripVoid() throws {
+        try jsRoundTripVoid()
     }
 
-    func testRoundTripNumber() {
+    func testRoundTripNumber() throws {
         for v in [
             0, 1, -1,
             Double(Int32.max), Double(Int32.min),
@@ -17,34 +17,71 @@ class ImportAPITests: XCTestCase {
             Double.infinity,
             Double.pi,
         ] {
-            XCTAssertEqual(jsRoundTripNumber(v), v)
+            try XCTAssertEqual(jsRoundTripNumber(v), v)
         }
 
-        XCTAssert(jsRoundTripNumber(Double.nan).isNaN)
+        try XCTAssert(jsRoundTripNumber(Double.nan).isNaN)
     }
 
-    func testRoundTripBool() {
+    func testRoundTripBool() throws {
         for v in [true, false] {
-            XCTAssertEqual(jsRoundTripBool(v), v)
+            try XCTAssertEqual(jsRoundTripBool(v), v)
         }
     }
 
-    func testRoundTripString() {
+    func testRoundTripString() throws {
         for v in ["", "Hello, world!", "🧑‍🧑‍🧒"] {
-            XCTAssertEqual(jsRoundTripString(v), v)
+            try XCTAssertEqual(jsRoundTripString(v), v)
         }
     }
 
-    func testClass() {
-        let greeter = JsGreeter("Alice", "Hello")
-        XCTAssertEqual(greeter.greet(), "Hello, Alice!")
-        greeter.changeName("Bob")
-        XCTAssertEqual(greeter.greet(), "Hello, Bob!")
+    func ensureThrows<T>(_ f: (Bool) throws(JSException) -> T) throws {
+        do {
+            _ = try f(true)
+            XCTFail("Expected exception")
+        } catch {
+            XCTAssertTrue(error.description.contains("TestError"))
+        }
+    }
+    func ensureDoesNotThrow<T>(_ f: (Bool) throws(JSException) -> T, _ assertValue: (T) -> Void) throws {
+        do {
+            let result = try f(false)
+            assertValue(result)
+        } catch {
+            XCTFail("Expected no exception")
+        }
+    }
+
+    func testThrowOrVoid() throws {
+        try ensureThrows(jsThrowOrVoid)
+        try ensureDoesNotThrow(jsThrowOrVoid, { _ in })
+    }
+
+    func testThrowOrNumber() throws {
+        try ensureThrows(jsThrowOrNumber)
+        try ensureDoesNotThrow(jsThrowOrNumber, { XCTAssertEqual($0, 1) })
+    }
+
+    func testThrowOrBool() throws {
+        try ensureThrows(jsThrowOrBool)
+        try ensureDoesNotThrow(jsThrowOrBool, { XCTAssertEqual($0, true) })
+    }
+
+    func testThrowOrString() throws {
+        try ensureThrows(jsThrowOrString)
+        try ensureDoesNotThrow(jsThrowOrString, { XCTAssertEqual($0, "Hello, world!") })
+    }
+
+    func testClass() throws {
+        let greeter = try JsGreeter("Alice", "Hello")
+        XCTAssertEqual(try greeter.greet(), "Hello, Alice!")
+        try greeter.changeName("Bob")
+        XCTAssertEqual(try greeter.greet(), "Hello, Bob!")
 
-        greeter.name = "Charlie"
-        XCTAssertEqual(greeter.greet(), "Hello, Charlie!")
-        XCTAssertEqual(greeter.name, "Charlie")
+        try greeter.setName("Charlie")
+        XCTAssertEqual(try greeter.greet(), "Hello, Charlie!")
+        XCTAssertEqual(try greeter.name, "Charlie")
 
-        XCTAssertEqual(greeter.prefix, "Hello")
+        XCTAssertEqual(try greeter.prefix, "Hello")
     }
 }
diff --git a/Tests/BridgeJSRuntimeTests/bridge-js.d.ts b/Tests/BridgeJSRuntimeTests/bridge-js.d.ts
index 664dd447..b03ef570 100644
--- a/Tests/BridgeJSRuntimeTests/bridge-js.d.ts
+++ b/Tests/BridgeJSRuntimeTests/bridge-js.d.ts
@@ -2,6 +2,10 @@ export function jsRoundTripVoid(): void
 export function jsRoundTripNumber(v: number): number
 export function jsRoundTripBool(v: boolean): boolean
 export function jsRoundTripString(v: string): string
+export function jsThrowOrVoid(shouldThrow: boolean): void
+export function jsThrowOrNumber(shouldThrow: boolean): number
+export function jsThrowOrBool(shouldThrow: boolean): boolean
+export function jsThrowOrString(shouldThrow: boolean): string
 
 export class JsGreeter {
     name: string;
@@ -9,4 +13,4 @@ export class JsGreeter {
     constructor(name: string, prefix: string);
     greet(): string;
     changeName(name: string): void;
-}
\ No newline at end of file
+}
diff --git a/Tests/prelude.mjs b/Tests/prelude.mjs
index 0d49045b..c6ac428a 100644
--- a/Tests/prelude.mjs
+++ b/Tests/prelude.mjs
@@ -19,6 +19,29 @@ export async function setupOptions(options, context) {
             "jsRoundTripString": (v) => {
                 return v;
             },
+            "jsThrowOrVoid": (shouldThrow) => {
+                if (shouldThrow) {
+                    throw new Error("TestError");
+                }
+            },
+            "jsThrowOrNumber": (shouldThrow) => {
+                if (shouldThrow) {
+                    throw new Error("TestError");
+                }
+                return 1;
+            },
+            "jsThrowOrBool": (shouldThrow) => {
+                if (shouldThrow) {
+                    throw new Error("TestError");
+                }
+                return true;
+            },
+            "jsThrowOrString": (shouldThrow) => {
+                if (shouldThrow) {
+                    throw new Error("TestError");
+                }
+                return "Hello, world!";
+            },
             JsGreeter: class {
                 /**
                  * @param {string} name