fix(alert): unhandled promise exception

src/components/alert/alert-component.ts

@@ -259,7 +259,9 @@ export class AlertCmp {
     }
 
     if (shouldDismiss) {
-      this.dismiss(button.role);
+      this.dismiss(button.role).catch(() => {
+        console.debug('alert can not be dismissed');
+      });
     }
   }
 

src/components/tabs/test/advanced/app.module.ts

@@ -81,6 +81,7 @@ export class TabsPage {
               alert.dismiss().then(() => {
                 resolve();
               });
+              return false;
             }
           }
         ]