message: raise exception early
diff: @@ -1232,7 +1232,10 @@ class Superset(BaseSupersetView):
  # The case where the datasource has been deleted
  datasource_id = None if datasource_id == 'None' else datasource_id
  - datasource_id = int(datasource_id) if datasource_id else None
  + if not datasource_id:
  + raise Exception(
  + 'The data source associated with this chart no longer exists')
  + datasource_id = int(datasource_id)
  return datasource_id, datasource_type
  @log_this
  