docs: def error(self):
          """**DEPRECATED**: Get the error if one occurred on the last operation.
  
          This method is obsolete: all MongoDB write operations (insert, update,
          remove, and so on) use the write concern ``w=1`` and report their
          errors by default.
  
          .. versionchanged:: 2.8
             Deprecated.
          """
          warnings.warn("Database.error() is deprecated",
                        DeprecationWarning, stacklevel=2)
  
          error = self.command("getlasterror")
          error_msg = error.get("err", "")
          if error_msg is None:
              return None
          if error_msg.startswith("not master"):
              # Reset primary server and request check, if another thread isn't
              # doing so already.
              primary = self.__client.primary
              if primary:
                  self.__client._reset_server_and_request_check(primary)
          return error