next build failed to import web workers from pure esm packages

[yume-chan]

Run next info (available from version 12.0.8 and up)

'yarn' is not recognized as an internal or external command,
operable program or batch file.
'pnpm' is not recognized as an internal or external command,
operable program or batch file.

    Operating System:
      Platform: win32
      Arch: x64
      Version: Windows 10 Pro
    Binaries:
      Node: 16.13.1
      npm: 8.1.2
      Yarn: N/A
      pnpm: N/A
    Relevant packages:
      next: 12.0.11-canary.1
      react: 17.0.2
      react-dom: 17.0.2

What version of Next.js are you using?

12.0.11-canary.1

What version of Node.js are you using?

v16.13.1

What browser are you using?

Unrelated

What operating system are you using?

Windows 11

How are you deploying your application?

Unrelated

Describe the Bug

When a dependency package has "type": "module" in package.json, and uses new Worker(new URL("./worker.js", import.meta.url)) to create a web worker, next build failed with

Module not found: ESM packages (./worker.js) need to be imported. Use 'import' to reference the package instead. https://nextjs.org/docs/messages/import-esm-externals

While next dev and a barebone webpack configuration all works.

---

This issue originated near here:

next.js/packages/next/build/webpack-config.ts

Lines 849 to 851 in 5365f41

	// When in esm externals mode, and using import, we resolve with
	// ESM resolving options.
	const isEsmRequested = dependencyType === 'esm'

dependencyType is "worker" in this case.

Expected Behavior

next build successfully create a build.

To Reproduce

git clone https://github.com/yume-chan/next-repro-33914
cd next-import-worker
npm i
cd packages/next-app
next build

The webpack-app folder is a barebone webpack configuration, which can correctly import and bundle the worker.

[christoph-pflueger]

I'm experiencing a similar issue. In my case the error during next build is

> next build

   ▲ Next.js 14.0.4
   - Experiments (use at your own risk):
     · esmExternals

Failed to compile.

static/media/worker.1494bc9b.js from Terser
  x 'import', and 'export' cannot be used outside of module code
    ,-[38:1]
[...]

Caused by:
    0: failed to parse input file
    1: Syntax Error


> Build failed because of webpack errors
   Creating an optimized production build  . ELIFECYCLE  Command failed with exit code 1.