Processing AuthStates
Processing AuthStates are AuthStates that do not authenticate a user. They may offer some additional functionality.
A processing AuthState may require an authenticated user set in the session, in which case this processing AuthState must be preceded by an authenticating AuthState. Note that the authenticating AuthState does not have to be the immediate predecessor of this processing AuthState. If no user is set in the session, a processing AuthState may try to load it or return with an error.