onLogin = () => {
  const { email, password } = this.state;
  firebase.auth().signInWithEmailAndPassword(email, password)
    .then((user) => {
      // If you need to do anything with the user, do it here
      // The user will be logged in automatically by the 
      // `onAuthStateChanged` listener we set up in App.js earlier
    })
    .catch((error) => {
      const { code, message } = error;
      // For details of error codes, see the docs
      // The message contains the default Firebase string
      // representation of the error
    });
}

onRegister = () => {
  const { email, password } = this.state;
  firebase.auth().createUserWithEmailAndPassword(email, password)
    .then((user) => {
      // If you need to do anything with the user, do it here
      // The user will be logged in automatically by the
      // `onAuthStateChanged` listener we set up in App.js earlier
    })
    .catch((error) => {
      const { code, message } = error;
      // For details of error codes, see the docs
      // The message contains the default Firebase string
      // representation of the error
    });
}