message: Fix 500 error when loading dashboards with slice having deleted dataset
diff: @@ -237,6 +237,7 @@ class Dashboard( # pylint: disable=too-many-instance-attributes
  # Filter out unneeded fields from the datasource payload
  datasource.uid: datasource.data_for_slices(slices)
  for datasource, slices in datasource_slices.items()
  + if datasource
  },
  }
  