code: def error_messages(self, driver_id=None):
          
          if driver_id is not None:
              assert isinstance(driver_id, ray.DriverID)
              return self._error_messages(driver_id)
  
          error_table_keys = self.redis_client.keys(
              ray.gcs_utils.TablePrefix_ERROR_INFO_string + "*")
          driver_ids = [
              key[len(ray.gcs_utils.TablePrefix_ERROR_INFO_string):]
              for key in error_table_keys
          ]
  
          return {
              binary_to_hex(driver_id): self._error_messages(
                  ray.DriverID(driver_id))
              for driver_id in driver_ids
          }
docs: Get the error messages for all drivers or a specific driver.
  
          Args:
              driver_id: The specific driver to get the errors for. If this is
                  None, then this method retrieves the errors for all drivers.
  
          Returns:
              A dictionary mapping driver ID to a list of the error messages for
                  that driver.