[utils] Make ExtractorError mutable

Closes #5674

yt_dlp/extractor/common.py

@@ -692,16 +692,10 @@ def extract(self, url):
         except UnsupportedError:
             raise
         except ExtractorError as e:
-            kwargs = {
-                'video_id': e.video_id or self.get_temp_id(url),
-                'ie': self.IE_NAME,
-                'tb': e.traceback or sys.exc_info()[2],
-                'expected': e.expected,
-                'cause': e.cause
-            }
-            if hasattr(e, 'countries'):
-                kwargs['countries'] = e.countries
-            raise type(e)(e.orig_msg, **kwargs)
+            e.video_id = e.video_id or self.get_temp_id(url),
+            e.ie = e.ie or self.IE_NAME,
+            e.traceback = e.traceback or sys.exc_info()[2]
+            raise
         except http.client.IncompleteRead as e:
             raise ExtractorError('A network error has occurred.', cause=e, expected=True, video_id=self.get_temp_id(url))
         except (KeyError, StopIteration) as e:

yt_dlp/extractor/youtube.py

@@ -4085,7 +4085,7 @@ def process_language(container, base_url, lang_code, sub_name, query):
                     if not trans_code:
                         continue
                     orig_trans_code = trans_code
-                    if caption_track.get('kind') != 'asr':
+                    if caption_track.get('kind') != 'asr' and trans_code != 'und':
                         if not get_translated_subs:
                             continue
                         trans_code += f'-{lang_code}'

yt_dlp/utils.py

@@ -1095,13 +1095,16 @@ def __init__(self, msg, tb=None, expected=False, cause=None, video_id=None, ie=N
         self.exc_info = sys.exc_info()  # preserve original exception
         if isinstance(self.exc_info[1], ExtractorError):
             self.exc_info = self.exc_info[1].exc_info
+        super().__init__(self.__msg)
 
-        super().__init__(''.join((
-            format_field(ie, None, '[%s] '),
-            format_field(video_id, None, '%s: '),
-            msg,
-            format_field(cause, None, ' (caused by %r)'),
-            '' if expected else bug_reports_message())))
+    @property
+    def __msg(self):
+        return ''.join((
+            format_field(self.ie, None, '[%s] '),
+            format_field(self.video_id, None, '%s: '),
+            self.orig_msg,
+            format_field(self.cause, None, ' (caused by %r)'),
+            '' if self.expected else bug_reports_message()))
 
     def format_traceback(self):
         return join_nonempty(
@@ -1109,6 +1112,12 @@ def format_traceback(self):
             self.cause and ''.join(traceback.format_exception(None, self.cause, self.cause.__traceback__)[1:]),
             delim='\n') or None
 
+    def __setattr__(self, name, value):
+        super().__setattr__(name, value)
+        if getattr(self, 'msg', None) and name not in ('msg', 'args'):
+            self.msg = self.__msg or type(self).__name__
+            self.args = (self.msg, )  # Cannot be property
+
 
 class UnsupportedError(ExtractorError):
     def __init__(self, url):