fix: make error handlers consistent with h3

[pi0]

This PR makes nitro default error handlers consistent and supports H3 error object features + adds tests to make sure they work in all presets and dev.

• Respecting custom error response headers
• Respecting custom error response body/data (toJSON implemented by HTTPError)
• Infer unhandled (if not set) by checking HTTPError.isError (same behavior as H3)
• Removed extra default CSP headers (json should not be loaded as source)
• Removed extra url key in response body
• Avoid duplicate console.error (H3 already console logs unhandled errors)

[vercel]

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

Project	Deployment	Actions	Updated (UTC)
nitro.build	Ready	Preview, Comment	Feb 27, 2026 6:17pm

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/errs

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}