Angular 18 production build doesn't work with vendor source maps

Start with the angular.json sourceMap configuration and compare the outputs of the documented ng serve and ng build commands using the production configuration. Reproduce the 404 for vendor source maps with Angular CLI 18.1.1, then trace the production build path to identify why node_modules maps are omitted. Done means production builds load vendor source maps while other source maps continue to work.

Which @angular/* package(s) are the source of the bug?

compiler-cli

Is this a regression?

Yes

Description

We upgraded our apps from ng17 to 18 and adopted the new build system. In our angular.json file we had options set to enable vendor source maps for production and regular builds. This worked fine prior to the upgrade. Example config below for references as I cannot post details from our work setup.

{
  "projects": {
    "your-project-name": {
      "architect": {
        "build": {
          "options": {
            "sourceMap": {
              "scripts": true,
              "vendor": true
            }
          }
        }
      }
    }
  }
}

So when running ng serve with a production config the source maps for things like RX are debuggable without issue.

ng serve application --open live-reload --configuration=production

However when we run our release jobs using this command we find the disted app does not support loading source maps from node_modules. All other source maps seem to work fine .

ng build application --configuration=production

I looked for a documented change here to see if vendor source maps are still supported in production builds and couldn't find anything about them being deprecated.

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

404 cannot load source map

Please provide the environment you discovered this bug in (run ng version)

Angular CLI Version: 18.1.1
Node Version: 20.11.1
Package Manager: npm 10.2.4
Operating System: win32 x64 (Windows 64-bit)


@angular-devkit/architect: 0.1801.1
@angular-devkit/build-angular: 18.1.1
@angular-devkit/core: 18.1.1
@angular-devkit/schematics: 18.1.1
@schematics/angular: 18.1.1
ng-packagr: 18.1.0
rxjs: 7.8.1
typescript: 5.5.4
webpack: 5.92.1
zone.js: 0.14.3

Anything else?

No response