I can't get token about codelab-friendlychat-android HOT 4 CLOSED

A bad HTTP response code (404) was received when fetching the script. :5001/__/firebase/3.8.0/firebase-app.js 

Failed to load resource: net::ERR_INVALID_RESPONSE firebase-messaging-sw.js:1 

Uncaught [object DOMException] (anonymous) @ firebase-messaging-sw.js:1
main.js:237 

Unable to get messaging token. e {code: "messaging/failed-serviceworker-registration", message: "Messaging: We are unable to register the default s…ed (messaging/failed-serviceworker-registration).", 

browserErrorMessage: "Failed to register a ServiceWorker: ServiceWorker script evaluation failed", stack: "FirebaseError: Messaging: We are unable to registe….gstatic.com/firebasejs/3.8.0/firebase.js:544:225"}
(anonymous) @ main.js:237

importScripts('https://www.gstatic.com/firebasejs/4.1.1/firebase-app.js');
importScripts('https://www.gstatic.com/firebasejs/4.1.1/firebase-messaging.js');
importScripts('https://www.gstatic.com/firebasejs/4.1.1/firebase.js');


var config = {
    apiKey: "<APIKEY>",
    authDomain: "<PROJECTID>.firebaseapp.com",
    databaseURL: "https://<DATABASE NAME>.firebaseio.com",
    projectId: "<PROJECT ID>",
    storageBucket: "<PROJECT ID>.appspot.com",
    messagingSenderId: "<SENDER ID>"
};
firebase.initializeApp(config);
const messaging = firebase.messaging();

messaging.setBackgroundMessageHandler(function(payload) {
    console.log('[firebase-messaging-sw.js] Received background message ', payload);
    // Customize notification here
    const notificationTitle = 'Background Message Title';
    const notificationOptions = {
        body: 'Background Message body.',
        icon: '/firebase-logo.png'
    };

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

<script src="/__/firebase/4.1.3/firebase.js"></script>
<script src="/__/firebase/init.js"></script>