firebase.notifications（）.OnNotificationOpen多次调用

我调用了firebase.notifications（）.OnNotificationOpen on componentDidMount并在componentWillUnmount（）上删除它，但当应用程序从后台删除时，它似乎从未将其删除，因为它已注册多次。下面是我使用的代码，让我知道我做错了什么

        notificationOpenedListener = firebase.notifications().onNotificationOpened((notificationOpen: any) => {
        console.log("onNotificationOpened", notificationOpen);
        notificationOpen &&  notificationOpen.notification && notificationOpen.notification._data && notificationOpen.notification._data.extra && setTimeout(() => {
               }, 500);
    });

 async componentDidMount() {
        this.notificationOpenedListener = 
        firebase.notifications().onNotificationOpened((notificationOpen: any) => {});
  }

componentWillUnmount() {
      this.notificationOpenedListener();
  }