[Bug] - monaco-editor-webpack-plugin fails to load workers cross-origin (esm)

[RoccoC]

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Link

N/A

Monaco Editor Playground Code

N/A

Reproduction Steps

In order to repro, you'll need a project depending on monaco-editor@>=0.52.0 and [email protected]. The plugin should be configured to load the workers from a different origin than the host.

Actual (Problematic) Behavior

I'm running into an issue in my project after upgrading to [email protected] where the language workers fail to load:

This appears to be caused by the monaco-editor-webpack-plugin, which falls back to using importScripts() when loading these workers cross-origin (in my case, the host origin is localhost:8100, and scripts are served by webpack-dev-server on localhost:8105). importScripts() is only supported for "classic" workers and fails when workers are initialized with type: "module" (https://developer.mozilla.org/en-US/docs/Web/API/WorkerGlobalScope/importScripts#typeerror).

Looks like this was caused by recent changes to the monaco-editor core as part of the ESM migration (here), where workers are now instantiated as module workers.

I believe the fix for this is to update the webpack plugin's getWorkerUrl function (here) to support ESM environments.

Expected Behavior

The worker should successfully load and not result in a TypeError.

Additional Context

I've raised #4742 to update the plugin to support ESM workers.