The TeacherPortalAuthenticate middleware called Auth::guard('sanctum')
without a try-catch, unlike MultiAuth and EnsurePrintRequestsAdminAccess
which already handle the InvalidArgumentException gracefully when the
sanctum guard driver is not yet registered.
This caused 'Auth guard [sanctum] is not defined' errors in tests when
the SanctumServiceProvider's driver registration hadn't completed before
middleware execution.