Issue in LSP stopping Jupyterlab Build

Hi, I am facing an issue in jupyterlab build. The issue seems to originate from LSP. No solution online seems to work. Errorlog from “jupter lab build”

[LabBuildApp] Building in /cr/users/koundal/miniconda3/share/jupyter/lab
[LabBuildApp] Node v12.4.0

[LabBuildApp] Yarn configuration loaded.
[LabBuildApp] Building jupyterlab assets (production, minimized)
[LabBuildApp] > node /cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/staging/yarn.js install --non-interactive
[LabBuildApp] yarn install v1.21.1
[1/5] Validating package.json...
[2/5] Resolving packages...
success Already up-to-date.
Done in 0.64s.

[LabBuildApp] > node /cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/staging/yarn.js yarn-deduplicate -s fewer --fail
[LabBuildApp] yarn run v1.21.1
$ /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/.bin/yarn-deduplicate -s fewer --fail
Done in 1.25s.

[LabBuildApp] > node /cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/staging/yarn.js run build:prod:minimize
[LabBuildApp] yarn run v1.21.1
$ webpack --config webpack.prod.minimize.config.js
[webpack-cli] ModuleNotFoundError: Module not found: Error: Can't resolve '@jupyterlab-classic/application' in '/cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/lib'
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/Compilation.js:1656:28
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/NormalModuleFactory.js:708:13
    at eval (eval at create (/cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:10:1)
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/NormalModuleFactory.js:272:22
    at eval (eval at create (/cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:9:1)
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/NormalModuleFactory.js:401:22
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/NormalModuleFactory.js:118:11
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/NormalModuleFactory.js:632:24
    at /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/webpack/lib/NormalModuleFactory.js:781:5
    at finishWithoutResolve (/cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/enhanced-resolve/lib/Resolver.js:296:11)
resolve '@jupyterlab-classic/application' in '/cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/lib'
  Parsed request is a module
  using description file: /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/package.json (relative path: ./lib)
    Field 'browser' doesn't contain a valid alias configuration
    resolve as module
      /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/lib/node_modules doesn't exist or is not a directory
      looking for modules in /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/node_modules
        single file module
          using description file: /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/package.json (relative path: ./node_modules/@jupyterlab-classic/application)
            no extension
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/node_modules/@jupyterlab-classic/application doesn't exist
            .js
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/node_modules/@jupyterlab-classic/application.js doesn't exist
            .json
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/node_modules/@jupyterlab-classic/application.json doesn't exist
            .wasm
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/node_modules/@jupyterlab-classic/application.wasm doesn't exist
        /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/jupyterlab-lsp/node_modules/@jupyterlab-classic/application doesn't exist
      /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@krassowski/node_modules doesn't exist or is not a directory
      /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/node_modules doesn't exist or is not a directory
      looking for modules in /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules
        single file module
          using description file: /cr/users/koundal/miniconda3/share/jupyter/lab/staging/package.json (relative path: ./node_modules/@jupyterlab-classic/application)
            no extension
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@jupyterlab-classic/application doesn't exist
            .js
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@jupyterlab-classic/application.js doesn't exist
            .json
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@jupyterlab-classic/application.json doesn't exist
            .wasm
              Field 'browser' doesn't contain a valid alias configuration
              /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@jupyterlab-classic/application.wasm doesn't exist
        /cr/users/koundal/miniconda3/share/jupyter/lab/staging/node_modules/@jupyterlab-classic/application doesn't exist
      /cr/users/koundal/miniconda3/share/jupyter/lab/node_modules doesn't exist or is not a directory
      /cr/users/koundal/miniconda3/share/jupyter/node_modules doesn't exist or is not a directory
      /cr/users/koundal/miniconda3/share/node_modules doesn't exist or is not a directory
      /cr/users/koundal/miniconda3/node_modules doesn't exist or is not a directory
      looking for modules in /cr/users/koundal/node_modules
        single file module
          No description file found in /cr/users/koundal/node_modules/@jupyterlab-classic or above
          no extension
            Field 'browser' doesn't contain a valid alias configuration
            /cr/users/koundal/node_modules/@jupyterlab-classic/application doesn't exist
          .js
            Field 'browser' doesn't contain a valid alias configuration
            /cr/users/koundal/node_modules/@jupyterlab-classic/application.js doesn't exist
          .json
            Field 'browser' doesn't contain a valid alias configuration
            /cr/users/koundal/node_modules/@jupyterlab-classic/application.json doesn't exist
          .wasm
            Field 'browser' doesn't contain a valid alias configuration
            /cr/users/koundal/node_modules/@jupyterlab-classic/application.wasm doesn't exist
        /cr/users/koundal/node_modules/@jupyterlab-classic/application doesn't exist
      /cr/users/node_modules doesn't exist or is not a directory
      /cr/node_modules doesn't exist or is not a directory
      /node_modules doesn't exist or is not a directory
error Command failed with exit code 2.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

[LabBuildApp] JupyterLab failed to build
[LabBuildApp] Traceback (most recent call last):

[LabBuildApp]   File "/cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/debuglog.py", line 47, in debug_logging
    yield

[LabBuildApp]   File "/cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/labapp.py", line 168, in start
    raise e

[LabBuildApp]   File "/cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/labapp.py", line 165, in start
    app_options=app_options, production = production, minimize=self.minimize)

[LabBuildApp]   File "/cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/commands.py", line 470, in build
    production=production, minimize=minimize, clean_staging=clean_staging)

[LabBuildApp]   File "/cr/users/koundal/miniconda3/lib/python3.7/site-packages/jupyterlab/commands.py", line 678, in build
    raise RuntimeError(msg)

[LabBuildApp] RuntimeError: JupyterLab failed to build

[LabBuildApp] Exiting application: JupyterLab

[jasongrout]

Might be worth including in the cookiecutter

Would you mind opening an issue in the cookiecutter to track that idea?

[jasongrout]

I made https://github.com/jupyterlab/jupyterlab/issues/9807 to track making it officially supported how to publish an npm package that is not a source extension, but which is the basis of a prebuilt extension.