JSON.stringify of builder aggregate error returns empty object

[nobkd]

What version of Bun is running?

1.2.0-canary.43+5819fe49a

What platform is your computer?

Linux 6.12.9-200.fc41.x86_64 x86_64 unknown

What steps can reproduce the bug?

Run first with 1.1.45+196621f25, then again with e.g. 1.2.0-canary.43+5819fe49a and compare the error object:

import { promises as fs } from 'node:fs'

// create erroneous css file
const filename = 'test.css'
await fs.writeFile(filename, 'body margin: 0 }')

try {
    // build
    const result = await Bun.build({ entrypoints: [filename], minify: true, experimentalCss: true })

    // on build failure: is run until at least 1.1.45+196621f25, not run on 1.2.0-canary.43+5819fe49a
    if (!result.success) {
        console.log('Manual throw:')
        throw result.logs[0]
    }

    // do sth. with result, not relevant here

} catch(e) {
    console.error(e)
    console.log('---')
    console.error('Error Object:', JSON.stringify(e, null, 2))

    // cleanup
    await fs.rm(filename, { force: true })
}

This errors with the following error in both versions (as expected):

error: Unexpected end of input
    at /.../test.css:1:17

Which is correct and expected, but the error data I get is different.

What is the expected behavior?

Having an error object with details about the build error

(looks like the following in 1.1.45+196621f25)

something like:

{
  "name": "BuildMessage",
  "position": {
    "lineText": "body margin: 0 }",
    "file": "/.../test.css",
    "namespace": "file",
    "line": 1,
    "column": 17,
    "length": 0,
    "offset": 0
  },
  "message": "Unexpected end of input",
  "level": "error"
}

What do you see instead?

no error object

(looks like the following in 1.2.0-canary.43+5819fe49a)

{}

Additional information

In previous versions, the Bun.build command returned a success: false key on the result object, and the logs property contained error information.

The new variant throws an error directly, but has no error information attached.

I don't really care, how this gets handled, as long, as I get appropriate error data, that can be processed in JS :)

[nobkd]

Oh, I haven't checked, if its the same for non-css building. I just tested it only with css.

[paperclover]

the new behavior is intentionally throwing an AggregateError, see https://bun.sh/docs/bundler#logs-and-errors. This change was made after seeing most users forget to handle success: false, or worse forget to await the promise at all.

However, I did not check that JSON.stringify actually works, to which it seems to not work. We should fix that.

Maybe you can iterate and read errors individually with e.errors (array of message)

[nobkd]

Ah, I didn't think about e.errors. Using that works fine. Thank you. Good luck with the stringification of the aggregate error :)