[ie/youtube] Make initial n function name search non-fatal

Authored by: bashonly

yt_dlp/extractor/youtube/_video.py

@@ -2150,7 +2150,7 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
     def _extract_n_function_name(self, jscode, player_url=None):
         varname, global_list = self._interpret_player_js_global_var(jscode, player_url)
         if debug_str := traverse_obj(global_list, (lambda _, v: v.endswith('_w8_'), any)):
-            return self._search_regex(
+            funcname = self._search_regex(
                 r'''(?xs)
                     [;\n](?:
                         (?P<f>function\s+)|
@@ -2161,7 +2161,12 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                     \}\s*catch\(\s*[a-zA-Z0-9_$]+\s*\)\s*
                     \{\s*return\s+%s\[%d\]\s*\+\s*(?P=argname)\s*\}\s*return\s+[^}]+\}[;\n]
                 ''' % (re.escape(varname), global_list.index(debug_str)),
-                jscode, 'nsig function name', group='funcname')
+                jscode, 'nsig function name', group='funcname', default=None)
+            if funcname:
+                return funcname
+            self.write_debug(join_nonempty(
+                'Initial search was unable to find nsig function name',
+                player_url and f'        player = {player_url}', delim='\n'), only_once=True)
 
         # Examples (with placeholders nfunc, narray, idx):
         # *  .get("n"))&&(b=nfunc(b)