Error ocurred when listing posts withouth date metadata

[zerasul]

File "e:\blask\blask\Blask\blaskapp.py", line 124, in _gettag
postlist = self.blogrenderer.list_posts([tag])
File "e:\blask\blask\Blask\blogrenderer.py", line 124, in list_posts
entries = list(sorted(entries, key=lambda t: t.date, reverse=True))
TypeError: '<' not supported between instances of 'datetime.datetime' and 'NoneType'