From b9e110b9ebdc171e19423eca87e90d0347f56182 Mon Sep 17 00:00:00 2001
From: Nolann Biron <biron.nolann@gmail.com>
Date: Wed, 30 Jul 2025 15:02:20 +0200
Subject: [PATCH] Fix merge logic for allOf alternatives

---
 .changeset/tame-months-knock.md              |  5 +++++
 packages/react-openapi/src/OpenAPISchema.tsx | 18 +++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)
 create mode 100644 .changeset/tame-months-knock.md

diff --git a/.changeset/tame-months-knock.md b/.changeset/tame-months-knock.md
new file mode 100644
index 0000000000..5f2d1457b2
--- /dev/null
+++ b/.changeset/tame-months-knock.md
@@ -0,0 +1,5 @@
+---
+'@gitbook/react-openapi': patch
+---
+
+Fix merge logic for allOf alternatives
diff --git a/packages/react-openapi/src/OpenAPISchema.tsx b/packages/react-openapi/src/OpenAPISchema.tsx
index 7c5e71d812..ee808f3a0a 100644
--- a/packages/react-openapi/src/OpenAPISchema.tsx
+++ b/packages/react-openapi/src/OpenAPISchema.tsx
@@ -556,8 +556,10 @@ function mergeAlternatives(
                     schemaOrRef.enum
                 ) {
                     const keys = Object.keys(schemaOrRef);
-                    if (keys.every((key) => ['type', 'enum', 'nullable'].includes(key))) {
-                        latest.enum = Array.from(new Set([...latest.enum, ...schemaOrRef.enum]));
+                    if (keys.some((key) => ['type', 'enum', 'nullable'].includes(key))) {
+                        latest.enum = Array.from(
+                            new Set([...(latest.enum || []), ...(schemaOrRef.enum || [])])
+                        );
                         latest.nullable = latest.nullable || schemaOrRef.nullable;
                         return acc;
                     }
@@ -566,18 +568,20 @@ function mergeAlternatives(
                 if (latest && latest.type === 'object' && schemaOrRef.type === 'object') {
                     const keys = Object.keys(schemaOrRef);
                     if (
-                        keys.every((key) =>
+                        keys.some((key) =>
                             ['type', 'properties', 'required', 'nullable'].includes(key)
                         )
                     ) {
                         latest.properties = {
-                            ...latest.properties,
-                            ...schemaOrRef.properties,
+                            ...(latest.properties || {}),
+                            ...(schemaOrRef.properties || {}),
                         };
                         latest.required = Array.from(
                             new Set([
-                                ...(Array.isArray(latest.required) ? latest.required : []),
-                                ...(Array.isArray(schemaOrRef.required)
+                                ...(latest.required && Array.isArray(latest.required)
+                                    ? latest.required
+                                    : []),
+                                ...(schemaOrRef.required && Array.isArray(schemaOrRef.required)
                                     ? schemaOrRef.required
                                     : []),
                             ])