fix(core): avoid error handling on cancelled requests to prevent crash

[pwrwpw]

TLDR

Fix crash caused by accessing error properties on cancelled requests.
Checks for request cancellation early and gracefully handles it to prevent runtime errors.

Dive Deeper

When a user cancels a request (e.g., by pressing ESC), the error handling code attempts to read properties from an undefined error object, causing a crash.
This change moves the cancellation check before any error processing, so if the request is aborted, the code emits a cancellation event and exits cleanly without throwing exceptions or processing undefined errors.

Reviewer Test Plan

• Send requests and cancel them using ESC abort signals.

• Verify that no unnecessary exception handling occurs upon cancellation.

• Verify that the UserCancelled event is emitted appropriately on cancellation.

• Ensure that normal errors (e.g., UnauthorizedError) are still handled correctly.

Testing Matrix

	🍏	🪟	🐧
npm run	✅	❓	❓
npx	❓	❓	❓
Docker	❓	❓	❓
Podman	❓	-	-
Seatbelt	❓	-	-

Linked issues / bugs

Fixes #5935

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[gemini-code-assist]

Summary of Changes

Hello @pwrwpw, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical crash that occurred when users cancelled ongoing requests. The fix reorders the error handling logic to first check if a request has been aborted. By doing so, the system can gracefully handle cancellations, preventing attempts to access undefined error properties and ensuring a clean exit. This change maintains the correct handling of other error types, such as unauthorized access, while significantly improving the stability of request cancellation.

Highlights

• Crash Fix for Cancelled Requests: The core issue addressed is a crash that occurs when a user cancels a request, leading to attempts to access properties on an undefined error object within the error handling flow.
• Prioritized Cancellation Handling: The solution involves reordering the error handling logic to check for request cancellation (signal.aborted) before attempting to process any potential errors. This ensures that if a request is aborted, the system gracefully exits and emits a UserCancelled event without triggering further errors.
• Preservation of Existing Error Handling: The change ensures that while cancelled requests are handled gracefully, the system still correctly processes and throws UnauthorizedError instances and reports other general errors as intended.

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[gemini-code-assist]

Code Review

This pull request addresses a critical crash that occurs when a request is cancelled. The fix involves moving the cancellation check to the beginning of the catch block, ensuring that cancelled requests are handled gracefully before any other error processing occurs. This prevents potential runtime errors from attempting to access properties on a malformed error object. The change is logical, robust, and correctly prioritizes user-initiated cancellations. I approve this change.

[jacob314]

Thanks for the pr. If you can follow up with a adding a quick test to ensure we don't regress that would be helpful to make sure we don't regress and reintroduce a bug.

[pwrwpw]

/gemini

[gemini-code-assist]

Hello @pwrwpw, I've received your request for a code review. Here's my assessment of your pull request:

Overall Review

This pull request effectively addresses a critical crash scenario by reordering the cancellation check within the Turn class's error handling logic. The change ensures that if a request is aborted, the system gracefully handles the cancellation and avoids attempting to process potentially malformed error objects, which previously led to a crash.

Detailed Review

packages/core/src/core/turn.ts

• Change: The if (signal.aborted) check has been moved to occur before the toFriendlyError(e) call.
• Impact: This is the core of the fix. By checking for cancellation first, the code prevents toFriendlyError from being called with a malformed error object when the request has been aborted. This directly resolves the crash described in the PR description.
• Correctness: critical - This change is essential for the stability and correctness of the application, preventing a runtime crash.

packages/core/src/core/turn.test.ts

• New Test Case: A new test should not crash when cancelled request has malformed error (reproduces 84d87c2a bug) has been added.
• Test Effectiveness: This test is excellent. It precisely mocks the sendMessageStream to simulate both cancellation and the malformed error condition, verifying that the UserCancelled event is emitted and that reportError is not called. This provides strong assurance that the fix works as intended and prevents regressions.
• Maintainability: high - Adding a specific test case for a previously identified bug significantly improves the maintainability and robustness of the codebase.

Conclusion

This is a well-executed fix for a significant issue. The code change is minimal but highly effective, and the accompanying test case thoroughly validates the solution. The pull request is ready to merge from a code quality and correctness perspective.

Great work, @pwrwpw!

[pwrwpw]

/gemini review

[gemini-code-assist]

Code Review

This pull request addresses a critical crash that occurs when a request is cancelled. The fix correctly prioritizes checking for request cancellation before attempting to process any associated error, which could be malformed and cause a runtime error. The change is logical, well-contained, and is accompanied by a specific test case that validates the fix by simulating the exact crash scenario. The implementation is sound and effectively resolves the reported issue.