No firebase app default has been create

firebase: No Firebase App '[DEFAULT]' has been created - call Firebase App.initializeApp()

//It means you have not initialized your app. 
//Maybe the location of the firebase_config file is written wrong. 
//Else you can initialise your app by this script:

var firebaseConfig = {
  apiKey: " <Provided by Firebase> ",
  authDomain: " <Provided by Firebase> ",
  projectId: " <Provided by Firebase> ",
  storageBucket: " <Provided by Firebase> ",
  databaseURL: " <Provided by Firebase> ",
  messagingSenderId: " <Provided by Firebase> ",
  appId: " <Provided by Firebase> ",
  measurementId: " <Provided by Firebase> "
  
};
// Initialize Firebase
firebase.initializeApp(firebaseConfig);
firebase.analytics();
var storage = firebase.storage();
var storageRef = firebase.storage().ref();