fix: use _notifyException to handle recoverSession errors

[dshukertjr]

What kind of change does this PR introduce?

Currently, the only way to listen to exceptions thrown during recoverSession is to handle SupabaseAuth.initialSession, which I think we should move away from, since it's a weird design pattern to just have a variable just for the initial session.

This PR allows users to listen to errors emitted on recoverSession by adding onError() on onAuthStateChanged. So that it is easier to handle the initial auth exceptions as well as on going exceptions happening during token refresh can be all handled through onAuthStateChanged.

[Vinzent03]

I like this! What about adding the stacktrace as optional argument to _notifiyException()?

[dshukertjr]

@Vinzent03 Ah, how could I forget that 😂