[something]Continuation renderers, all of which are junk
except one. Check the items in each one until the one which
contains the items being sought is found.
The usage in extract_comments_info needed to be changed to
specify the items being sought. It was unspecified before which
is strictly incorrect since extract_items by default looks for
video/playlist/channel thumbnail items. It was relying on this
special case for continuations. But now that wouldn't work
anymore.