Add formatError property to Blitz server- & rpchandler setup

[dbrxnds]

Closes: https://discord.com/channels/802917734999523368/1094607326108983400

What are the changes and their implications?

Add a formatError callback property to setupBlitzServer and rpcHandler. Allowing users to add custom logic before an error gets returned to the client.

Example: Showing less descriptive errors in production such as "Internal server error occured" rather than a complete Prisma error.

Questions

1. Would it be possible to pass the Blitz session public data to this callback function? This could allow for some logic based on roles / userid. I tried to make this work but I wasn't too sure about how to go about it, so I left it out for now.
2. Would it be okay to extract the statusCode from the formattedError (if there is one) and use that for the response?

Bug Checklist

• Changeset added (run pnpm changeset in the root directory)
• Integration test added (see test docs if needed)

Feature Checklist

• Changeset added (run pnpm changeset in the root directory)
• Integration test added (see test docs if needed)
• Documentation added/updated (submit PR to blitzjs.com repo main branch)

[changeset-bot]

🦋 Changeset detected

Latest commit: 3a25a84

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

Name	Type
@blitzjs/next	Minor
@blitzjs/rpc	Minor
next-blitz-auth	Patch
@blitzjs/auth	Minor
@blitzjs/codemod	Minor
@blitzjs/config	Minor
@blitzjs/generator	Minor
blitz	Patch

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[blitzjs-bot]

Added @dbrxnds contributions for doc, code and test