return nil
	}

	if !CDSUpdated && !LDSUpdated {
		return fmt.Errorf("config not received from XDS server (is Istiod running?): %s", s.String())
	} else if s.LDSUpdatesRejection > 0 || s.CDSUpdatesRejection > 0 {
		return fmt.Errorf("config received from XDS server, but was rejected: %s", s.String())
	}
	return fmt.Errorf("config not fully received from XDS server: %s", s.String())
}