Error accessing source map from npm package

[aeschli]

When running vscode web (serverless) I get the following warning about a source map not found:
GET /static/build/node_modules/@vscode/vscode-languagedetection/dist/lib/index.js.map 404 0.946 ms - 9

Either add the map file to the npm package, or, better, disable source maps when building for production to avoid the reference

To reproduce:

• git clone https://github.com/microsoft/vscode-test-web.git
• npm i && npm run sample, open dev tools network tab, in VS code web open some files