[common] fail only if the extractor didn't return formats

youtube_dl/YoutubeDL.py

@@ -1208,6 +1208,8 @@ class YoutubeDL(object):
             raise ExtractorError('Missing "id" field in extractor result')
         if 'title' not in info_dict:
             raise ExtractorError('Missing "title" field in extractor result')
+        if not info_dict.get('formats'):
+            raise ExtractorError('No video formats found')
 
         if 'playlist' not in info_dict:
             # It isn't part of a playlist

youtube_dl/extractor/common.py

@@ -765,7 +765,7 @@ class InfoExtractor(object):
 
     def _sort_formats(self, formats, field_preference=None):
         if not formats:
-            raise ExtractorError('No video formats found')
+            return
 
         def _formats_key(f):
             # TODO remove the following workaround