In my library, There is an interceptor that the user must provide in order for the component to work.

I want to throw an exception if the user forgets to provide the interceptor, maybe from a singleton service.

How can I achieve that?

export function progressInterceptor(req: HttpRequest<unknown>, next: HttpHandlerFn): Observable<HttpEvent<unknown>> {

  return next(req).pipe(
    finalize(() => {
      // some code
    })
  );
}

@Injectable({
  providedIn: 'root'
})
export class NgProgressHttpManager {

  constructor() {
    // Some how I need to access the list of provided interceptors!
    if (!interceptor instanceof NgProgressInterceptor) {
      throw new Error('NgProgressInterceptor is not provided. Please add it to the HTTP client interceptors.');
    }
  }
}

bootstrapApplication(AppComponent, {
  providers: [
    provideHttpClient(
      withInterceptors([
       // in case user forgot to add 'progressInterceptor'
      ])
    )
  ]
}).catch(err => console.error(err));