Varnish datadog exception

gistfile1.txt

 varnish
    -------
      - instance #0 [ERROR]: 'no element found: line 1, column 0'
        Traceback (most recent call last):
          File "/opt/datadog-agent/agent/checks/__init__.py", line 745, in run
            self.check(copy.deepcopy(instance))
          File "/opt/datadog-agent/agent/checks.d/varnish.py", line 93, in check
            self._parse_varnishstat(output, use_xml, tags)
          File "/opt/datadog-agent/agent/checks.d/varnish.py", line 178, in _parse_varnishstat
            p.Parse(output, True)
        ExpatError: no element found: line 1, column 0
        
      - Collected 0 metrics, 0 events & 1 service check