[instagram] Fix comment count extraction

youtube_dl/extractor/instagram.py

@@ -164,12 +164,18 @@ class InstagramIE(InfoExtractor):
             uploader = media.get('owner', {}).get('full_name')
             uploader_id = media.get('owner', {}).get('username')
 
-            def get_count(key, kind):
+            def get_count(keys, kind):
-                return int_or_none(try_get(
+                if not isinstance(keys, (list, tuple)):
+                    keys = [keys]
+                for key in keys:
+                    count = int_or_none(try_get(
                         media, (lambda x: x['edge_media_%s' % key]['count'],
                                 lambda x: x['%ss' % kind]['count'])))
+                    if count is not None:
+                        return count
             like_count = get_count('preview_like', 'like')
-            comment_count = get_count('to_comment', 'comment')
+            comment_count = get_count(
+                ('preview_comment', 'to_comment', 'to_parent_comment'), 'comment')
 
             comments = [{
                 'author': comment.get('user', {}).get('username'),