fix: prefer registered error code

[pupuking723]

Fixes #1919

When a custom error class defines its own code field, the runtime currently prefers that instance field over the key registered through .error(). That makes onError({ code }) receive a value that does not match the typed registered error key.

This changes both the AOT and dynamic error handlers to prefer the internal ERROR_CODE registration symbol, falling back to error.code for built-in errors and unregistered errors.

Verification:

• npx -y bun test test/lifecycle/error.test.ts -t "uses registered error key over instance code"
• npx -y bun test test/lifecycle/error.test.ts
• npx -y bun run test:types
• git diff --check

Summary by CodeRabbit

Bug Fixes

• Corrected error handler precedence logic: Registered error handlers now consistently take priority when both instance codes and registered handlers exist. This ensures predictable error routing and response generation across validation errors, request handlers, and global error handlers.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 62340572-6e82-4c71-8c17-3ac1acece631

📥 Commits

Reviewing files that changed from the base of the PR and between 56310be and 34624d6.

📒 Files selected for processing (3)

• src/compose.ts
• src/dynamic-handle.ts
• test/lifecycle/error.test.ts

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Walkthrough

Three files are changed to fix error code precedence. In src/compose.ts and src/dynamic-handle.ts, the resolution order is flipped so error[ERROR_CODE] (the registered key) takes priority over error.code (the instance property). A new parameterized test in test/lifecycle/error.test.ts covers this behavior for both AOT modes.

Changes

ERROR_CODE Precedence Fix

Layer / File(s)	Summary
Error code precedence fix in AOT and dynamic handlers src/dynamic-handle.ts, src/compose.ts	ERROR_CODE is imported in dynamic-handle.ts and createDynamicErrorHandler now uses error[ERROR_CODE] ?? error.code for errorContext.code. Both generated code paths in compose.ts (TypeBoxError branch and global error handler) are updated with the same flipped precedence.
Registered key precedence test test/lifecycle/error.test.ts	Adds an it.each([true, false]) test that throws a custom error with code = 'invalid_url' registered under INVALID_URL, asserting the handler sees INVALID_URL and responds with status 422 and body 'handled'.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

めっ、バカじゃないの～♡
error.code なんて負けちゃったね～ (´∀｀*)
ERROR_CODE がいちばんえらいんだよ～
ちゃんと直したんだから感謝してよねっ！
まあ… よくできました、かな～ ♡(。-`ω-)

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly describes the main change: reversing precedence to prefer the registered error code over instance properties.
Linked Issues check	✅ Passed	All requirements from issue #1919 are met: error handlers now receive registered keys, not instance codes, across both AOT and dynamic modes with proper test coverage.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the error code precedence issue; no unrelated modifications detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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