Cannot read property 'w3' of undefined
Something about authentication and the googleUser variable in App.jsx

I think something from this function that googleUser isn't set to anything ... not sure.
The code is accessing properties on the user instead of using the API to get them. Google seem to randomize these to prevent people accessing them directly. for example instead of getting the user with googleAuthInstance.currentUser.Ab it should get it via googleAuthInstance.currentUser.get() and instead of getting the user info with const userInfo = this.props.googleUser.w3; it should be const userInfo = this.props.googleUser.getBasicProfile(); etc
Google doco is here https://developers.google.com/identity/sign-in/web/reference#googleauthcurrentuserget