fix: type plain onError return as error status response

[zacharywomack8-source]

@algora-pbc /claim #313

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Type-level fix for #313 (Option to return errors as JSON).

Problem
An onError handler that returns a plain value (e.g. { error: '...' } or a string) is currently typed as if the response is 200. At runtime the response keeps the status of the error that triggered the handler (400/404/422/500), so the types lie about what the client receives.

Change

• Plain values returned from onError are now typed under every built-in error status (400, 404, 422, 500) instead of 200.
• Explicit status(code, ...) / error(code, ...) returns still resolve to their exact status code via ExtractErrorFromHandle.
• Applies to local, scoped, and global onError (single handler and array overloads), plus ErrorHandle composition in use/guard/macro.

Implementation

• Adds ErrorValueToResponseSchema, ElysiaErrorHandlerToResponseSchema, ElysiaErrorHandlerToResponseSchemas, ElysiaErrorHandlerToResponseSchemaAmbiguous in src/types.ts.
• Swaps the new types into the onError overloads and the ErrorHandle guards in src/index.ts.

Verification

• Updated test/types/lifecycle/soundness.ts onError expectations: plain returns now produce the error-status union instead of 200.
• pnpm test:types passes.

Summary by CodeRabbit

• Improvements
  • Improved type inference for error-handler responses across local, scoped, and global error handling.
  • Error responses now accurately reflect supported status codes, including 400, 404, 422, and 500.
  • Enhanced type handling for single, multiple, and ambiguous error handlers.
• Tests
  • Updated type-safety checks to validate the refined error response behavior.

claim-recheck-marker

[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 Plus

Run ID: 70109022-727e-4c7b-b31a-248e30ded7a0

📥 Commits

Reviewing files that changed from the base of the PR and between 89088df and da62021.

📒 Files selected for processing (3)

• src/index.ts
• src/types.ts
• test/types/lifecycle/soundness.ts

Included review availability: Your plan includes up to 10 reviews per rolling hour; 9 remain after this review.

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Walkthrough

This change adds error-handler-specific response inference types. It applies them to onError, group, and guard declarations. Type-soundness expectations now cover statuses 400, 404, 422, and 500.

Changes

Error response inference

Layer / File(s)	Summary
Error-handler response inference types src/types.ts	Adds response schema utilities for single handlers, handler arrays, and ambiguous handlers. Non-undefined returns map to statuses 400, 404, 422, and 500.
Lifecycle type integration src/index.ts	Applies the new utilities to global, scoped, and local onError, group, and guard declarations.
Type-soundness expectations test/types/lifecycle/soundness.ts	Updates local, scoped, and global onError expectations. Removes the previous 200 response and adds the inferred error statuses.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to da620

This PR corrects the reported type mismatch for plain values returned by error handlers while preserving explicit status handling; no actionable merge-blocking risk remains after normal checks and review.

Possibly related PRs

• elysiajs/elysia#1932: Introduces related error-handler response inference and maps plain onError returns to status 500.
• elysiajs/elysia#1942: Extends the related inference with array and ambiguous-handler variants for onError, group, and guard.

Poem

Error types gather, statuses align ♡
Four hundred paths now clearly shine~
Arrays merge their schemas neat,
Guards and groups keep types complete.
No stray 200, silly thing—
Error responses wear their ring~ (￣▽￣)♡

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the main change: correcting plain onError return types to use error status responses.
Description check	✅ Passed	The description explains the problem, implementation, affected APIs, related issue, and type-test verification in sufficient detail.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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