FixFirebaseAuthPart.js

  firebase.auth().signInWithCredential(credential)
        .then((user) => {
          console.log('facebook auth:', user);
          this.setState({name: user.email, modalVisible: false});
        })
        .catch((error) => {
          // Handle Errors here.
          this.setState({name: 'Anonymous', modalVisible: true});
          alert("An error occured: " + error.message);
        });