Drive: fix "UnboundLocalError: local variable 'local_folder' referenced before assignment" when offline state is notified

if info.online:
    local_folder = server_binding.local_folder
    # Mark binding as offline and update UI
    log.debug('Switching to offline mode (reason: %s) for: %s',
              reason, server_binding.local_folder)
    info.online = False
    self.update_running_icon()
    self.communicator.menu.emit()

if code == 401:
    log.debug('Detected invalid credentials for: %s', local_folder)
    self.communicator.invalid_credentials.emit(local_folder)