From 6d3a67b7a9cbbceeaeba2d5e3c21cb406a8bc47a Mon Sep 17 00:00:00 2001
From: HKWinterhalter <HansWinterhalter@gmail.com>
Date: Tue, 22 Aug 2023 03:42:47 -0700
Subject: [PATCH] fix: log actual errors instead of just strings with
 console.error so that Cloud Logging can detect error severity level correctly

---
 src/loader.ts  | 22 ++++++++++++----------
 src/main.ts    |  9 ++-------
 test/loader.ts | 12 ++++--------
 3 files changed, 18 insertions(+), 25 deletions(-)

diff --git a/src/loader.ts b/src/loader.ts
index b1a2d6cc..9ff20348 100644
--- a/src/loader.ts
+++ b/src/loader.ts
@@ -26,6 +26,13 @@ import {HandlerFunction} from './functions';
 import {SignatureType} from './types';
 import {getRegisteredFunction} from './function_registry';
 
+export class LoaderError extends Error {
+  constructor(message) {
+    super('Could not load the function: ' + message)
+    this.name = 'LoaderError'
+  }
+}
+
 // Dynamic import function required to load user code packaged as an
 // ES module is only available on Node.js v13.2.0 and up.
 //   https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import#browser_compatibility
@@ -93,23 +100,21 @@ export async function getUserFunction(
   try {
     const functionModulePath = getFunctionModulePath(codeLocation);
     if (functionModulePath === null) {
-      console.error(
+      throw new LoaderError(
         `Provided code location '${codeLocation}' is not a loadable module.` +
           '\nDid you specify the correct location for the module defining ' +
           'your function?'
       );
-      return null;
     }
 
     let functionModule;
     const esModule = await isEsModule(functionModulePath);
     if (esModule) {
       if (semver.lt(process.version, MIN_NODE_VERSION_ESMODULES)) {
-        console.error(
+        throw new LoaderError(
           `Cannot load ES Module on Node.js ${process.version}. ` +
             `Please upgrade to Node.js v${MIN_NODE_VERSION_ESMODULES} and up.`
         );
-        return null;
       }
       // Resolve module path to file:// URL. Required for windows support.
       const fpath = pathToFileURL(functionModulePath);
@@ -136,19 +141,17 @@ export async function getUserFunction(
       }, functionModule);
 
     if (typeof userFunction === 'undefined') {
-      console.error(
+      throw new LoaderError(
         `Function '${functionTarget}' is not defined in the provided ` +
           'module.\nDid you specify the correct target function to execute?'
       );
-      return null;
     }
 
     if (typeof userFunction !== 'function') {
-      console.error(
+      throw new LoaderError(
         `'${functionTarget}' needs to be of type function. Got: ` +
           `${typeof userFunction}`
       );
-      return null;
     }
 
     return {userFunction: userFunction as HandlerFunction, signatureType};
@@ -163,11 +166,10 @@ export async function getUserFunction(
     } else {
       additionalHint = 'Is there a syntax error in your code?\n';
     }
-    console.error(
+    throw new LoaderError(
       `Provided module can't be loaded.\n${additionalHint}` +
         `Detailed stack trace: ${err.stack}`
     );
-    return null;
   }
 }
 
diff --git a/src/main.ts b/src/main.ts
index 4aaaba1c..06013f88 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -38,11 +38,6 @@ export const main = async () => {
       options.target,
       options.signatureType
     );
-    if (!loadedFunction) {
-      console.error('Could not load the function, shutting down.');
-      // eslint-disable-next-line no-process-exit
-      process.exit(1);
-    }
     const {userFunction, signatureType} = loadedFunction;
     const server = getServer(userFunction!, signatureType);
     const errorHandler = new ErrorHandler(server);
@@ -58,8 +53,8 @@ export const main = async () => {
       })
       .setTimeout(0); // Disable automatic timeout on incoming connections.
   } catch (e) {
-    if (e instanceof OptionsError) {
-      console.error(e.message);
+    if (e instanceof OptionsError || e instanceof LoaderError) {
+      console.error(e);
       // eslint-disable-next-line no-process-exit
       process.exit(1);
     }
diff --git a/test/loader.ts b/test/loader.ts
index 1fd2968b..e5dc2716 100644
--- a/test/loader.ts
+++ b/test/loader.ts
@@ -94,23 +94,19 @@ describe('loading function', () => {
   }
 
   it('fails to load a module that does not exist', async () => {
-    const loadedFunction = await loader.getUserFunction(
+    expect(await loader.getUserFunction(
       process.cwd() + '/test/data/does_not_exist',
       'functionDoesNotExist',
       'http'
-    );
-
-    assert.strictEqual(loadedFunction, null);
+    )).toThrowErrorOfType(LoaderError);
   });
 
   it('fails to load a function that does not exist', async () => {
-    const loadedFunction = await loader.getUserFunction(
+    expect(await loader.getUserFunction(
       process.cwd() + '/test/data/with_main',
       'functionDoesNotExist',
       'http'
-    );
-
-    assert.strictEqual(loadedFunction, null);
+    )).toThrowErrorOfType(LoaderError);
   });
 
   it('loads a declaratively registered function', async () => {