fix(android): Use componentStack as fallback for missing error stack traces

CHANGELOG.md

@@ -10,6 +10,7 @@
 
 ### Fixes
 
+- Use React `componentStack` as fallback when error has no stack trace on Android ([#5071](https://github.com/getsentry/sentry-react-native/issues/5071))
 - Add `SENTRY_PROJECT_ROOT` env var to override project root in Xcode build phase scripts for monorepo setups ([#5961](https://github.com/getsentry/sentry-react-native/pull/5961))
 
 ### Features

packages/core/src/js/integrations/reactnativeerrorhandlers.ts

@@ -170,6 +170,15 @@ function setupErrorUtilsGlobalHandler(): void {
       return;
     }
 
+    // React render errors may arrive without a .stack but with a .componentStack
+    // (set by ReactFiberErrorDialog). Use the componentStack as a fallback so
+    // eventFromException can extract frames with source locations.
+    // oxlint-disable-next-line typescript-eslint(no-unsafe-member-access)
+    if (!error.stack && error.componentStack) {
+      // oxlint-disable-next-line typescript-eslint(no-unsafe-member-access)
+      error.stack = `${error.message || 'Error'}${error.componentStack}`;
+    }
+
     const hint: EventHint = {
       originalException: error,
       attachments: getCurrentScope().getScopeData().attachments,

packages/core/test/integrations/reactnativeerrorhandlers.test.ts

@@ -140,6 +140,40 @@ describe('ReactNativeErrorHandlers', () => {
 
       expect(hint).toEqual(expect.objectContaining({ originalException: new Error('Test Error') }));
     });
+
+    test('Uses componentStack as fallback when error has no stack', async () => {
+      const integration = reactNativeErrorHandlersIntegration();
+      integration.setupOnce!();
+
+      const error: any = {
+        message: 'Value is undefined, expected an Object',
+        componentStack:
+          '\n    at UserMessage (http://localhost:8081/index.bundle:1:5274251)' +
+          '\n    at renderItem (http://localhost:8081/index.bundle:1:5280705)',
+      };
+
+      await errorHandlerCallback!(error, true);
+      await client.flush();
+
+      expect(error.stack).toBe(
+        'Value is undefined, expected an Object' +
+          '\n    at UserMessage (http://localhost:8081/index.bundle:1:5274251)' +
+          '\n    at renderItem (http://localhost:8081/index.bundle:1:5280705)',
+      );
+    });
+
+    test('Does not override stack when error already has one', async () => {
+      const integration = reactNativeErrorHandlersIntegration();
+      integration.setupOnce!();
+
+      const error = new Error('Test Error');
+      (error as any).componentStack = '\n    at SomeComponent (http://localhost:8081/index.bundle:1:100)';
+      const originalStack = error.stack;
+
+      await errorHandlerCallback!(error, false);
+
+      expect(error.stack).toBe(originalStack);
+    });
   });
 
   describe('onUnhandledRejection', () => {