fix: NotificationService does not remove references to closed notifications

Author: markewallace

src/notification/notification.service.ts

@@ -145,7 +145,7 @@ export class NotificationService implements OnDestroy {
 					this.applicationRef.detachView(notificationRef.hostView);
 					notificationRef.destroy();
 					const index = this.notificationRefs.indexOf(notificationRef);
-					if (index != -1) {
+					if (index !== -1) {
 						this.notificationRefs.splice(index, 1);
 					}
 				}, 200);