fix(service-worker): avoid uncaught rejection warning when registration fails (#30876)

Service worker API `navigator.serviceWorker.register` can fail in multiple ways.
For example, in Chrome, with an unstable network connection you can have the
following error: `An unknown error occurred when fetching the script.`

In the current state, it creates an `Uncaught (in promise) TypeError:` style of
error, which cannot be caught by the user on his own.

I think it's better to log the error over raising an error that cannot be
caught.

PR Close #30876

Author: H--o-l

packages/service-worker/src/module.ts

@@ -115,10 +115,11 @@ export function ngswAppInitializer(
       }
     }
 
-    // Don't return anything to avoid blocking the application until the SW is registered or
-    // causing a crash if the SW registration fails.
+    // Don't return anything to avoid blocking the application until the SW is registered.
+    // Catch and log the error if SW registration fails to avoid uncaught rejection warning.
     readyToRegister$.pipe(take(1)).subscribe(
-        () => navigator.serviceWorker.register(script, {scope: options.scope}));
+        () => navigator.serviceWorker.register(script, {scope: options.scope})
+                  .catch(err => console.error('Service worker registration failed with:', err)));
   };
   return initializer;
 }

packages/service-worker/test/module_spec.ts

@@ -28,7 +28,9 @@ describe('ServiceWorkerModule', () => {
     return appRef.isStable.pipe(filter(Boolean), take(1)).toPromise();
   };
 
-  beforeEach(() => swRegisterSpy = spyOn(navigator.serviceWorker, 'register'));
+  beforeEach(
+      () => swRegisterSpy =
+          spyOn(navigator.serviceWorker, 'register').and.returnValue(Promise.resolve()));
 
   describe('register()', () => {
     const configTestBed = async(opts: SwRegistrationOptions) => {
@@ -67,6 +69,15 @@ describe('ServiceWorkerModule', () => {
       expect(TestBed.get(SwUpdate).isEnabled).toBe(true);
       expect(swRegisterSpy).toHaveBeenCalledWith('sw.js', {scope: undefined});
     });
+
+    it('catches and a logs registration errors', async() => {
+      const consoleErrorSpy = spyOn(console, 'error');
+      swRegisterSpy.and.returnValue(Promise.reject('no reason'));
+
+      await configTestBed({enabled: true, scope: 'foo'});
+      expect(consoleErrorSpy)
+          .toHaveBeenCalledWith('Service worker registration failed with:', 'no reason');
+    });
   });
 
   describe('SwRegistrationOptions', () => {