fix(nitro): skip default logging for expected evlog 4xx errors

[evlogai]

Refs EVL-534. Closes #814.

Change

evlog's Nitro error handlers (src/nitro/errorHandler.ts for v2, src/nitro-v3/errorHandler.ts for v3) call Nitro's ctx.defaultHandler whenever the dev overlay is not suppressed. In production that is always the case, so Nitro printed every thrown createError as [request error] [unhandled] with a stack dump, on top of the wide event evlog already writes.

The handlers now skip defaultHandler when the error is an EvlogError with a status below 500. The check lives in a new isExpectedEvlogError helper in src/nitro.ts. 5xx EvlogErrors and non-evlog errors are still logged by Nitro.

Behavior change to review

The skip applies whatever the dev preset, so dev: 'nitro' or 'both' no longer shows Nitro's overlay for expected 4xx EvlogErrors either. Those errors are still in the wide event. If you want the overlay kept in dev, the check can be scoped to non-dev.

Evidence

Unit tests

Regression test written first, run on main before the fix (test/nitro/errorHandler.test.ts, same case in test/nitro-v3/errorHandler.test.ts):

FAIL  skips Nitro default logging for an expected 4xx EvlogError in production
AssertionError: expected "vi.fn()" to not be called at all, but actually been called 1 times
  [EvlogError: Payment failed], { _handled: true, ... }, { silent: false }

After the fix: both files pass, 45 tests. The 5xx case passes before and after.

End to end (Nitro v2, production build)

Run in apps/nitro-v2-playground with NODE_ENV=production nitropack build and node .output/server/index.mjs, then GET /api/test/error, which throws createError({ status: 400, why, fix, link }).

On main (038de6a):

HTTP 400
{"url":"/api/test/error","status":400,...,"data":{"why":"Card declined by issuer","fix":"Try a different payment method","link":"https://docs.example.com/payments/declined"}}

[request error] [unhandled] [GET] http://localhost:3132/api/test/error
 EvlogError: Payment processing failed
    at createError (...)
  statusCode: 400,
  fatal: false,
  unhandled: true,
  ...

On this branch (3d3387e), same request:

HTTP 400
{"url":"/api/test/error","status":400,...,"data":{"why":"Card declined by issuer","fix":"Try a different payment method","link":"https://docs.example.com/payments/declined"}}

No [request error] line. The response body is identical in both runs.

5xx check on this branch, using a temporary route that throws createError({ status: 503 }) (removed afterward): Nitro still prints [request error] [unhandled] with the stack, and the wide event is still written with statusCode: 503.

The playground prints [evlog] ... called after the wide event was emitted warnings in both runs. They come from the playground route and are unrelated to this change.

Checks

• pnpm run lint: pass
• pnpm run typecheck: pass (after dev:prepare for apps/telemetry; the first run failed there only because its .nuxt directory was missing)
• pnpm --filter evlog exec vitest run: 100 of 100 test files pass
• Nitro suites: 125 tests pass after pnpm --filter evlog build

Not verified

• The reproduction uses Nitro v2 through apps/nitro-v2-playground, not a full Nuxt app. The Nitro v3 handler is covered by unit tests only.

ELI5

When a request fails for an expected reason, such as a declined card, evlog already writes one clear log line. Nitro, the server under Nuxt, was also printing a long "unhandled error" block for it. This change stops Nitro from printing that block for expected 4xx errors. Real server failures are still printed.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
evi	Ready	Preview	Oct 10, 2026 6:51pm UTC
evlog-docs	Ready	Preview, v0	Oct 10, 2026 6:51pm UTC
evlog-render-lab	Ready	Preview	Oct 10, 2026 6:51pm UTC
evlog-telemetry	Ready	Preview	Oct 10, 2026 6:51pm UTC
just-use-evlog	Ready	Preview	Oct 10, 2026 6:51pm UTC

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commit: 3d3387e