fix(angular): swiping back quickly no longer causes app to get stuck (#23125)

resolves #15154

Author: capc0

angular/src/directives/navigation/ion-router-outlet.ts

@@ -52,7 +52,7 @@ export class IonRouterOutlet implements OnDestroy, OnInit {
     this._swipeGesture = swipe;
 
     this.nativeEl.swipeHandler = swipe ? {
-      canStart: () => this.stackCtrl.canGoBack(1),
+      canStart: () => this.stackCtrl.canGoBack(1) && !this.stackCtrl.hasRunningTask(),
       onStart: () => this.stackCtrl.startBackTransition(),
       onEnd: shouldContinue => this.stackCtrl.endBackTransition(shouldContinue)
     } : undefined;

angular/src/directives/navigation/stack-controller.ts

@@ -232,6 +232,10 @@ export class StackController {
     return this.activeView ? this.activeView.stackId : undefined;
   }
 
+  hasRunningTask(): boolean {
+    return this.runningTask !== undefined;
+  }
+
   destroy() {
     this.containerEl = undefined!;
     this.views.forEach(destroyView);
@@ -294,6 +298,7 @@ export class StackController {
       this.runningTask = undefined;
     }
     const promise = this.runningTask = task();
+    promise.finally(() => this.runningTask = undefined);
     return promise;
   }
 }