code: def show_error(self, message):
          
          assert isinstance(message, string_types)
          self.post('error', data=message)
docs: Send an error message to the active client. The new error will be
              displayed on any active GUI clients.
  
              Args:
                  message (str): Plain-text message to display.
  
              Returns:
                  None
  
              >>> s = _syncthing()
              >>> s.system.show_error('my error msg')
              >>> s.system.errors()[0]
              ... # doctest: +ELLIPSIS
              ErrorEvent(when=datetime.datetime(...), message='"my error msg"')
              >>> s.system.clear_errors()
              >>> s.system.errors()
              []