error: Cannot read properties of undefined (reading 'INTERNAL')

[HALL 9000]

Hello,

I created a code by following a vidéo course. The code is strikly the same and the dependences also. I checked all several time, all is correct.

This is my code, you can make modification as you want, it's a forked version:
https://stackblitz.com/edit/react-jeffgc?file=src%2FApp.js,src%2Fbase.js

That doesn't works anymore from the moment I try to connect whith firebase using base.js file.
In App.js file if you comment the  lines under 8, you will see the code running correctly:

//import base from './base';

 /*componentDidMount() {
    base.syncState('/', {
      context: this,
      state: 'messages',
    });
  }*/

I'm beginner and I really need help to finshed the tuto. I jnow that the firebase 's version used is old but I think I am obligated to use same version that in the tuto.

What's wrong in my code ?