[extractor/youtube] Make signature extraction non-fatal

and reduce verbosity of it's warning

Closes #3882

yt_dlp/extractor/youtube.py

@@ -2530,22 +2530,16 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
     def _decrypt_signature(self, s, video_id, player_url):
         """Turn the encrypted s field into a working signature"""
-
-        if player_url is None:
-            raise ExtractorError('Cannot decrypt signature without player_url')
-
         try:
             player_id = (player_url, self._signature_cache_id(s))
             if player_id not in self._player_cache:
-                func = self._extract_signature_function(
-                    video_id, player_url, s
-                )
+                func = self._extract_signature_function(video_id, player_url, s)
                 self._player_cache[player_id] = func
             func = self._player_cache[player_id]
             self._print_sig_code(func, s)
             return func(s)
         except Exception as e:
-            raise ExtractorError('Signature extraction failed: ' + traceback.format_exc(), cause=e)
+            raise ExtractorError(traceback.format_exc(), cause=e, video_id=video_id)
 
     def _decrypt_nsig(self, s, video_id, player_url):
         """Turn the encrypted n field into a working signature"""
@@ -3147,13 +3141,17 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 sc = compat_parse_qs(fmt.get('signatureCipher'))
                 fmt_url = url_or_none(try_get(sc, lambda x: x['url'][0]))
                 encrypted_sig = try_get(sc, lambda x: x['s'][0])
-                if not (sc and fmt_url and encrypted_sig):
+                if not all((sc, fmt_url, player_url, encrypted_sig)):
                     continue
-                if not player_url:
+                try:
+                    fmt_url += '&%s=%s' % (
+                        traverse_obj(sc, ('sp', -1)) or 'signature',
+                        self._decrypt_signature(encrypted_sig, video_id, player_url)
+                    )
+                except ExtractorError as e:
+                    self.report_warning('Signature extraction failed: Some formats may be missing', only_once=True)
+                    self.write_debug(e, only_once=True)
                     continue
-                signature = self._decrypt_signature(sc['s'][0], video_id, player_url)
-                sp = try_get(sc, lambda x: x['sp'][0]) or 'signature'
-                fmt_url += '&' + sp + '=' + signature
 
             query = parse_qs(fmt_url)
             throttled = False
@@ -3164,7 +3162,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
                 except ExtractorError as e:
                     self.report_warning(
                         'nsig extraction failed: You may experience throttling for some formats\n'
-                        f'n = {query["n"][0]} ; player = {player_url}\n{e}', only_once=True)
+                        f'n = {query["n"][0]} ; player = {player_url}', only_once=True)
+                    self.write_debug(e, only_once=True)
                     throttled = True
 
             if itag: