[servingsys] AttributeError: 'NoneType' object has no attribute 'text'

[ghost]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2019.09.28
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

[ServingSys] 5349193: Downloading XML
Traceback (most recent call last):
  File "/usr/bin/youtube-dl", line 10, in <module>
    sys.exit(main())
  File "/usr/lib/python3.7/site-packages/youtube_dl/__init__.py", line 474, in main
    _real_main(argv)
  File "/usr/lib/python3.7/site-packages/youtube_dl/__init__.py", line 464, in _real_main
    retcode = ydl.download(all_urls)
  File "/usr/lib/python3.7/site-packages/youtube_dl/YoutubeDL.py", line 2018, in download
    url, force_generic_extractor=self.params.get('force_generic_extractor', False))
  File "/usr/lib/python3.7/site-packages/youtube_dl/YoutubeDL.py", line 796, in extract_info
    ie_result = ie.extract(url)
  File "/usr/lib/python3.7/site-packages/youtube_dl/extractor/common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "/usr/lib/python3.7/site-packages/youtube_dl/extractor/servingsys.py", line 51, in _real_extract
    title = vast_doc.find('.//AdTitle').text
AttributeError: 'NoneType' object has no attribute 'text'

Description

I don't know why this extractor shouldn't be removed:
'http://bs.serving-sys.com/BurstingPipe/adServer.bs?cn=is&c=23&pl=VAST&pli=5349193&PluID=0&pos=7135&ord=[timestamp]&cim=1?'
'http://bs.serving-sys.com/BurstingPipe/adServer.bs?cn=is&c=23&pl=VAST&pli=13569296&PluID=0&pos=1886&ord=%%CACHEBUSTER%%&cim=1'