refactor(router): remove non-null assertions (#48244)

As part of #24571, removing non-null assertions (where appropriate)

PR Close #48244

packages/router/src/router_scroller.ts

@@ -19,10 +19,8 @@ export const ROUTER_SCROLLER = new InjectionToken<RouterScroller>('');
 
 @Injectable()
 export class RouterScroller implements OnDestroy {
-  // TODO(issue/24571): remove '!'.
-  private routerEventsSubscription!: Unsubscribable;
-  // TODO(issue/24571): remove '!'.
-  private scrollEventsSubscription!: Unsubscribable;
+  private routerEventsSubscription?: Unsubscribable;
+  private scrollEventsSubscription?: Unsubscribable;
 
   private lastId = 0;
   private lastSource: 'imperative'|'popstate'|'hashchange'|undefined = 'imperative';
@@ -105,11 +103,7 @@ export class RouterScroller implements OnDestroy {
 
   /** @nodoc */
   ngOnDestroy() {
-    if (this.routerEventsSubscription) {
-      this.routerEventsSubscription.unsubscribe();
-    }
-    if (this.scrollEventsSubscription) {
-      this.scrollEventsSubscription.unsubscribe();
-    }
+    this.routerEventsSubscription?.unsubscribe();
+    this.scrollEventsSubscription?.unsubscribe();
   }
 }

packages/router/src/router_state.ts

@@ -115,9 +115,9 @@ export class ActivatedRoute {
   /** @internal */
   _routerState!: RouterState;
   /** @internal */
-  _paramMap!: Observable<ParamMap>;
+  _paramMap?: Observable<ParamMap>;
   /** @internal */
-  _queryParamMap!: Observable<ParamMap>;
+  _queryParamMap?: Observable<ParamMap>;
 
   /** An Observable of the resolved route title */
   readonly title: Observable<string|undefined> =
@@ -288,17 +288,13 @@ export class ActivatedRouteSnapshot {
   /** @internal */
   _resolve: ResolveData;
   /** @internal */
-  // TODO(issue/24571): remove '!'.
-  _resolvedData!: Data;
+  _resolvedData?: Data;
   /** @internal */
-  // TODO(issue/24571): remove '!'.
   _routerState!: RouterStateSnapshot;
   /** @internal */
-  // TODO(issue/24571): remove '!'.
-  _paramMap!: ParamMap;
+  _paramMap?: ParamMap;
   /** @internal */
-  // TODO(issue/24571): remove '!'.
-  _queryParamMap!: ParamMap;
+  _queryParamMap?: ParamMap;
 
   /** The resolved route title */
   get title(): string|undefined {

packages/router/src/url_tree.ts

@@ -189,8 +189,7 @@ function matrixParamsMatch(
  */
 export class UrlTree {
   /** @internal */
-  // TODO(issue/24571): remove '!'.
-  _queryParamMap!: ParamMap;
+  _queryParamMap?: ParamMap;
 
   constructor(
       /** The root segment group of the URL tree */
@@ -299,8 +298,7 @@ export class UrlSegmentGroup {
  */
 export class UrlSegment {
   /** @internal */
-  // TODO(issue/24571): remove '!'.
-  _parameterMap!: ParamMap;
+  _parameterMap?: ParamMap;
 
   constructor(
       /** The path part of a URL segment */

packages/router/test/regression_integration.spec.ts

@@ -123,18 +123,18 @@ describe('Integration', () => {
         `
          })
          class ComponentWithRouterLink {
-           // TODO(issue/24571): remove '!'.
-           @ViewChild(TemplateRef, {static: true}) templateRef!: TemplateRef<any>;
-           // TODO(issue/24571): remove '!'.
+           @ViewChild(TemplateRef, {static: true}) templateRef?: TemplateRef<any>;
            @ViewChild('container', {read: ViewContainerRef, static: true})
-           container!: ViewContainerRef;
+           container?: ViewContainerRef;
 
            addLink() {
-             this.container.createEmbeddedView(this.templateRef, {$implicit: '/simple'});
+             if (this.templateRef) {
+               this.container?.createEmbeddedView(this.templateRef, {$implicit: '/simple'});
+             }
            }
 
            removeLink() {
-             this.container.clear();
+             this.container?.clear();
            }
          }