Support Angular 21

[aminesbdev]

The package only accepted Angular 22.2, because the enableTemplateSourceLocations compiler option only exists since 22.1.4. Angular 21 has the same feature in the compiler and the same attribute at runtime, but the only switch is setEnableTemplateSourceLocations(), a function that @angular/compiler exports for Angular's own tests.

What changes

• New entry point ngx-source-inspector/enable-source-locations, a preload for ng serve that calls that function in the process and in the worker thread that compile the templates:

  NODE_OPTIONS="--import ngx-source-inspector/enable-source-locations" ng serve

  It only does something for the dev server (ng serve, ng s, ng dev, a serve target), so a production build stays clean even when NODE_OPTIONS is set for it too. On Angular versions that have the compiler option it does nothing and says so.

• ng add looks at the installed Angular version. With the compiler option it does what it did before. Without it, it only adds the provider and prints the command above. It doesn't touch the start script, since the VAR=value command syntax isn't portable to Windows.

• Peer dependencies accept >=21.0.0 <23.0.0, and the version goes to 0.2.0.

How it was checked

• Unit tests for the preload (dev server commands, other commands, a compiler without the setter, outside of a workspace) and for the new ng add path.
• npm run check:angular-21, also run in CI: sets up a new Angular 21 app with ng add, checks that ng serve with the preload produces source locations and that a production build with the same NODE_OPTIONS contains none.
• By hand on Angular 21.2.25 in headless Chrome: Alt+hover shows <app-root> · src/app/app.html:235:7 on the <h1> of the new app, and Alt+click calls the editor with that file, line and column.

Not checked: Windows, and Angular 21.0, 21.1 and 22.0 to 22.1.3.

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