[YouTube] Avoid crash in author extraction

Thanks MatteoH2O1999: https://github.com/MatteoH2O1999/setup-python

.github/workflows/ci.yml

@@ -38,10 +38,12 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Set up supported Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v4
+      # wrap broken actions/setup-python@v4
-      if: ${{ matrix.python-impl == 'cpython' && ! contains(fromJSON('["3.3", "3.4"]'), matrix.python-version) }}
+      uses: ytdl-org/setup-python@v1
       with:
         python-version: ${{ matrix.python-version }}
+        cache-build: true
+        allow-build: info
     - name: Set up Java 8
       if: ${{ matrix.python-impl == 'jython' }}
       uses: actions/setup-java@v2

test/test_youtube_signature.py

@@ -63,11 +63,6 @@ _SIG_TESTS = [
         'https://s.ytimg.com/yts/jsbin/html5player-en_US-vflKjOTVq/html5player.js',
         '312AA52209E3623129A412D56A40F11CB0AF14AE.3EE09501CB14E3BCDC3B2AE808BF3F1D14E7FBF12',
         '112AA5220913623229A412D56A40F11CB0AF14AE.3EE0950FCB14EEBCDC3B2AE808BF331D14E7FBF3',
-    ),
-    (
-        'https://www.youtube.com/s/player/6ed0d907/player_ias.vflset/en_US/base.js',
-        '2aq0aqSyOoJXtK73m-uME_jv7-pT15gOFC02RFkGMqWpzEICs69VdbwQ0LDp1v7j8xx92efCJlYFYb1sUkkBSPOlPmXgIARw8JQ0qOAOAA',
-        'AOq0QJ8wRAIgXmPlOPSBkkUs1bYFYlJCfe29xx8j7v1pDL2QwbdV96sCIEzpWqMGkFR20CFOg51Tp-7vj_EMu-m37KtXJoOySqa0',
     )
 ]
 
@@ -157,8 +152,8 @@ _NSIG_TESTS = [
         'qO0NiMtYQ7TeJnfFG2', 'k9cuJDHNS5O7kQ',
     ),
     (
-        'https://www.youtube.com/s/player/8c7583ff/player_ias.vflset/en_US/base.js',
+        'https://www.youtube.com/s/player/b7910ca8/player_ias.vflset/en_US/base.js',
-        'E2AQVN6y_zM7uN9w8z', '9A2dbY5GDZrt9A',
+        '_hXMCwMt9qE310D', 'LoZMgkkofRMCZQ',
     ),
 ]
 
@@ -236,7 +231,7 @@ def n_sig(jscode, sig_input):
 
 
 make_sig_test = t_factory(
-    'signature', signature, re.compile(r'(?s).*(?:-|/player/)(?P<id>[a-zA-Z0-9_-]+)(?:/.+\.js|(?:/watch_as3|/html5player)?\.[a-z]+)$'))
+    'signature', signature, re.compile(r'.*-(?P<id>[a-zA-Z0-9_-]+)(?:/watch_as3|/html5player)?\.[a-z]+$'))
 for test_spec in _SIG_TESTS:
     make_sig_test(*test_spec)
 

youtube_dl/extractor/youtube.py

@@ -448,7 +448,7 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             extract_attributes(self._search_regex(
                 r'''(?s)(<link\b[^>]+\bitemprop\s*=\s*("|')%s\2[^>]*>)'''
                 % re.escape(var_name),
-                get_element_by_attribute('itemprop', 'author', webpage) or '',
+                get_element_by_attribute('itemprop', 'author', webpage or '') or '',
                 'author link', default='')),
             paths[var_name][0])
 
@@ -1623,15 +1623,22 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         nfunc, idx = re.match(target, nfunc_and_idx).group('nfunc', 'idx')
         if not idx:
             return nfunc
+
+        VAR_RE_TMPL = r'var\s+%s\s*=\s*(?P<name>\[(?P<alias>%s)\])[;,]'
+        note = 'Initial JS player n function {0} (%s[%s])' % (nfunc, idx)
+
+        def search_function_code(needle, group):
+            return self._search_regex(
+                VAR_RE_TMPL % (re.escape(nfunc), needle), jscode,
+                note.format(group), group=group)
+
         if int_or_none(idx) == 0:
-            real_nfunc = self._search_regex(
+            real_nfunc = search_function_code(r'[a-zA-Z_$][\w$]*', group='alias')
-                r'var %s\s*=\s*\[([a-zA-Z_$][\w$]*)\];' % (re.escape(nfunc), ), jscode,
-                'Initial JS player n function alias ({nfunc}[{idx}])'.format(**locals()))
             if real_nfunc:
                 return real_nfunc
-        return self._parse_json(self._search_regex(
+        return self._parse_json(
-            r'var %s\s*=\s*(\[.+?\]);' % (re.escape(nfunc), ), jscode,
+            search_function_code('.+?', group='name'),
-            'Initial JS player n function name ({nfunc}[{idx}])'.format(**locals())), nfunc, transform_source=js_to_json)[int(idx)]
+            nfunc, transform_source=js_to_json)[int(idx)]
 
     def _extract_n_function(self, video_id, player_url):
         player_id = self._extract_player_info(player_url)