Configuration for displaying error messages

[SiegeSailor]

Goals

1. Configuration in next.config.js: The current Next.js 15 error handling behavior is that it "hides" the real server errors and presents a digest hash value instead (see https://nextjs.org/docs/app/getting-started/error-handling). However, the server logs and the client terminal are not always reachable. It would be perfect to be able to configure it.

Non-Goals

No response

Background

I am developing a medical device, which runs Next.js on a purpose-built Linux ARM64 board. The application kept throwing an error that never appeared in development mode but showed up a lot in the standalone build (not even in other ARM64 machines). The board has a very low performance; its browser is cog (very minimum WPEKit), and the labs/hospitals usually don't have internet access. This gives me a tough time to debug. I have to reproduce it on my board without the actual hardware/firmware and environment setup, and trace back the change log to disable/enable configurations and features to "guess" what's wrong.

Errors I Have Seen

The SyntaxError throws a lot when I run the standalone build on the purpose-built Linux board. However, I have never seen this on macOS, Linux on AMD64, and even development mode on the purpose-built board:

 ⨯ SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>) {
  digest: '2367858545'
}

The following happens when the Next.js app crashes (refreshes the page unexpectedly):

⨯ [Error: The router state header was sent but could not be parsed.]

I am still not 100% sure about the cause. Could be low-available CPU so the event listeners accumulate too many, or the network overheads occupies the cog browser, or constant MongoDB connection/write/read failure. (Next.js, Python gRPC server, Nginx, custom Proxy server, and MongoDB are all running in a Docker container on the board)

Proposal

/** @type {import('next').NextConfig} */
const nextConfig = {
  ...,
  hideServerErrors: false // Default to `true`
  ...
}