Request: Always resolve source maps on Errors

[huw]

For this worker:

export default {
  fetch: async () => {
    console.error(new Error("Pretty error test"));
    return new Response("OK");
  },
};

I would expect the console.error call to print the error with a source mapped stack trace (like it does if I throw the error), but it doesn’t. I hunted through the Miniflare code and found that we do construct source maps for thrown errors, but don’t override prepareStackTrace by default.

I tried removing the line Error.prepareStackTrace = originalPrepareStackTrace; in getSourceMapper() and calling getSourceMapper() on launch, but it didn’t seem to override prepareStackTrace. Nor did passing NODE_OPTIONS=--source-map-support to wrangler dev.

I’m not expecting this to be fixed anytime soon (although I’ll happily take pointers on how to fix it myself!), but I wanted to raise the issue so it’s tracked somewhere. Cheers again for all the hard work on this repo, it’s not unappreciated ❤️

[frandiox]

I might be mistaken but I think that, in latest Miniflare 3, the error comes already stringified from Workerd and Miniflare just prints it without modifying the stack trace. Somewhere around here. Maybe that's the place to add sourcemaps 🤔

[mrbbot]

Hey! 👋 Yep, in Miniflare 3 (which I'm assuming this issue is for), we just see a string from workerd here:

miniflare/packages/miniflare/src/runtime/index.ts

Line 88 in b634851

stderr.on("line", (data) => console.error(red(data)));

This is the same problem as logging stacks to the console (i.e. console.log(new Error().stack));
There was a PR to workers-sdk to address this issue (cloudflare/workers-sdk#3739). We're planning on addressing that soon. 👍

[huw]

Can’t believe I didn’t see that—thank you! I’ll leave it to you to whether you wanna close this issue now or after that ships :)

[mrbbot]

Hey! 👋 Thanks for raising this issue. I was going to transfer this to workers-sdk as that's the new home for Miniflare 3, but considering we already have that PR and this is on our internal issue tracker, I'm going to close this.