如何修复“您的网站已在后台更新”（Firebase Cloud Messaging）

Question

最近，我在我的angular js项目中实现了FCM。 有时，我从Chrome收到“您的网站已在后台更新”的通知，而不是实际的通知。

为什么会这样？ 该问题的可能解决方法是什么？

if ('function' === typeof importScripts) {

    importScripts('https://www.gstatic.com/firebasejs/5.5.3/firebase-app.js');
    importScripts('https://www.gstatic.com/firebasejs/5.5.3/firebase-messaging.js');

    // TODO: fill in messaging sender id
    firebase.initializeApp({
      'messagingSenderId': 'MY SENDER ID'
    });

    const messaging = firebase.messaging();

    // Installs service worker
    self.addEventListener('install', (event) => {
      console.log('Service worker installed');
    });

    self.addEventListener('notificationclick', (event) => {
      // Event actions derived from event.notification.data from data received
      var eventURL = event.notification.data;
      event.notification.close();
      if (event.action === 'confirmAttendance') {
        clients.openWindow(eventURL.confirm);
      } else {
        clients.openWindow(eventURL.decline);
      }
    }, false);

    messaging.setBackgroundMessageHandler((payload) => {
      // Parses data received and sets accordingly

      const data = JSON.parse(payload.data.notification);
      const notificationTitle = data.title;
      const notificationOptions = {
        body: data.body,
        // icon: '/static/images/5/icons/android-icon-96x96.png',
        actions: [
          {action: 'confirmAttendance', title: ' Confirm attendance'},
          {action: 'cancel', title: ' Not coming'}
        ],
        // For additional data to be sent to event listeners, needs to be set in this data {}
        data: {confirm: data.confirm, decline: data.decline}
      };

      return self.registration.showNotification(notificationTitle, notificationOptions);
    });

  }