* [CssSelectorFeedExpander] Fix ArgumentCountError (#3739)
Fix ArgumentCountError (#3739) using new FeedParser class (#3740)
Implement default value for feed name / url if missing
* [CssSelectorFeedExpander] Skip empty fields in source feed
Fix empty feed properties being passed down from source feed
rssbridge.DEBUG lib/FeedItem.php(177): Author must be a string!
rssbridge.DEBUG lib/FeedItem.php(267): Unique id must be a string!
If "don't expand metadata" is checked, then source feed is passed
down verbatim (only content is expanded) so the debug messages
will persist, but the issue is in source feed, not in the bridge.