[extractor/NiconicoSeries] Fix extraction (#6898)

Authored by: sqrtNOT

yt_dlp/extractor/niconico.py

@@ -660,10 +660,10 @@ class NiconicoPlaylistIE(NiconicoPlaylistBaseIE):
 
 class NiconicoSeriesIE(InfoExtractor):
     IE_NAME = 'niconico:series'
-    _VALID_URL = r'https?://(?:(?:www\.|sp\.)?nicovideo\.jp|nico\.ms)/series/(?P<id>\d+)'
+    _VALID_URL = r'https?://(?:(?:www\.|sp\.)?nicovideo\.jp(?:/user/\d+)?|nico\.ms)/series/(?P<id>\d+)'
 
     _TESTS = [{
-        'url': 'https://www.nicovideo.jp/series/110226',
+        'url': 'https://www.nicovideo.jp/user/44113208/series/110226',
         'info_dict': {
             'id': '110226',
             'title': 'ご立派ァ！のシリーズ',
@@ -683,7 +683,7 @@ class NiconicoSeriesIE(InfoExtractor):
 
     def _real_extract(self, url):
         list_id = self._match_id(url)
-        webpage = self._download_webpage(f'https://www.nicovideo.jp/series/{list_id}', list_id)
+        webpage = self._download_webpage(url, list_id)
 
         title = self._search_regex(
             (r'<title>「(.+)（全',
@@ -691,10 +691,9 @@ class NiconicoSeriesIE(InfoExtractor):
             webpage, 'title', fatal=False)
         if title:
             title = unescapeHTML(title)
-        playlist = [
-            self.url_result(f'https://www.nicovideo.jp/watch/{v_id}', video_id=v_id)
-            for v_id in re.findall(r'data-href=[\'"](?:https://www\.nicovideo\.jp)?/watch/([a-z0-9]+)', webpage)]
-        return self.playlist_result(playlist, list_id, title)
+        json_data = next(self._yield_json_ld(webpage, None, fatal=False))
+        return self.playlist_from_matches(
+            traverse_obj(json_data, ('itemListElement', ..., 'url')), list_id, title, ie=NiconicoIE)
 
 
 class NiconicoHistoryIE(NiconicoPlaylistBaseIE):