After refreshing the page I lose the ability to retrieve user information

At first my webapp looses login after refresh, then I read some topics on how to set up social logins and I solved.
But now I have a different problem. Here is some code to explain better:

const { user } = useAuth0();

const sub = user.sub;

If I refresh I get: “TypeError: Cannot read property ‘sub’ of undefined
However, the user is still logged, in fact if I go back and then forward using the browser arrows, the page reloads without errors.
If I load login/signup page url, the “logout” button appears as the user is still logged.
I realized that maybe it’s not clear. The button if the user is not logged display"login", if user is logged display “logout”.

EDIT: From other tests I have done I have noticed this. If I refresh a component (use React.js) that retrieve user info like:, user.sub ecc… I get error; but if I load a different component first and then the one using user. then it works.

Concrete example: The UserInfo.js component crashes after the refresh, but if I first access the Dashboard.js component and then click on UserInfo through the sidebar then it works and load it without any error.

How can I avoid this error? And above all why does it occur if the user apparently has not logged out?

EDIT: I think I have identified the problem but I don’t know how to solve it: when the page is rendered, the response from the Auth0 API still not obtained and therefore the claim user.sub is undefined.
In the SDK there’s loading but I don’t know how to use it and I haven’t found any help about it.