Add icon to notifications

public/service_worker.js

@@ -5,7 +5,8 @@ self.addEventListener('push', function (event) {
 
     event.waitUntil(self.registration.showNotification(notification.title, {
       body: notification.body,
-      tag: notification.type
+      tag: notification.type,
+      icon: "/icons/maskable_icon_x128.png"
     }));
   } else {
     console.error("Push event received, but it didn't contain any data.", event);