Improve error handling of bad config files

Related: #824

yt_dlp/options.py

@@ -96,12 +96,16 @@ def load_configs():
 
     opts = optparse.Values({'verbose': True, 'print_help': False})
     try:
-        if overrideArguments:
-            root.append_config(overrideArguments, label='Override')
-        else:
-            root.append_config(sys.argv[1:], label='Command-line')
+        try:
+            if overrideArguments:
+                root.append_config(overrideArguments, label='Override')
+            else:
+                root.append_config(sys.argv[1:], label='Command-line')
+            loaded_all_configs = all(load_configs())
+        except ValueError as err:
+            raise root.parser.error(err)
 
-        if all(load_configs()):
+        if loaded_all_configs:
             # If ignoreconfig is found inside the system configuration file,
             # the user configuration is removed
             if root.parse_known_args()[0].ignoreconfig:
@@ -183,7 +187,7 @@ def parse_known_args(self, args=None, values=None, strict=True):
         return self.check_values(self.values, self.largs)
 
     def error(self, msg):
-        msg = f'{self.get_prog_name()}: error: {msg.strip()}\n'
+        msg = f'{self.get_prog_name()}: error: {str(msg).strip()}\n'
         raise optparse.OptParseError(f'{self.get_usage()}\n{msg}' if self.usage else msg)
 
     def _get_args(self, args):

yt_dlp/utils.py

@@ -5420,6 +5420,8 @@ def read_file(filename, default=[]):
             # FIXME: https://github.com/ytdl-org/youtube-dl/commit/dfe5fa49aed02cf36ba9f743b11b0903554b5e56
             contents = optionf.read()
             res = shlex.split(contents, comments=True)
+        except Exception as err:
+            raise ValueError(f'Unable to parse "{filename}": {err}')
         finally:
             optionf.close()
         return res