getExtUri error when using monaco-languageclient with Angular 20 (Angular build system)

[vishnuvarthan-balasubramaniam]

We are currently trying to integrate monaco-editor with monaco-languageclient to enable LSP (Language Server Protocol) support in an Angular 20 application using the standard Angular build system (Angular CLI / esbuild).

We have reviewed the Angular example provided in the repository, which is implemented using the Vite build system. That example works as expected. However, when attempting to achieve the same setup using Angular’s default build system, we consistently encounter a runtime error related to getExtUri, regardless of changes made to imports, modules, or package versions.

Environment

Framework: Angular 20
Build system: Angular CLI (default Angular build / esbuild)
Packages: monaco-languageclient v10.6.0

Could you please clarify one of the following:

1. Is the Angular CLI / Angular build system officially supported for monaco-languageclient?
2. Are there known limitations or required configurations when using Angular instead of Vite?
3. Is there an example repository demonstrating monaco-editor + monaco-languageclient using:
   • Angular CLI
   • Angular’s default build system (esbuild)
4. If Angular CLI is not supported at the moment, could this be documented explicitly?

We can provide a minimal reproduction repository if required.
Thank you for your time and support.

[kaisalmen]

Hi @vishnuvarthan-balasubramaniam we moved away from the Angular build system in our verification example as it broke the code during bundling for both development and production. Although angular build uses esbuild/vite internally you cannot use existing esbuild plugins like @codingame/esbuild-import-meta-url-plugin we use to overcome an issue we have with esbuild in vite dev mode as well.

Production builds are also broken with angular build. We don't see such issues with vite/rollup/rolldown. That is the reason we switched to @analogjs/vite-plugin-angular.

1. Is the Angular CLI / Angular build system officially supported for monaco-languageclient?

No, I will continue try in the future.

2. Are there known limitations or required configurations when using Angular instead of Vite?
3. Is there an example repository demonstrating monaco-editor + monaco-languageclient using:

• Angular CLI
• Angular’s default build system (esbuild)

You can to isolate the monaco-languageclient related code and pre-bundle your code and workers with rolldown. This is a strategy that works with next.js / Turbopack.

4. If Angular CLI is not supported at the moment, could this be documented explicitly?

Yes, I will do that.