Proper exception chaining.

discord/ext/commands/bot.py

@@ -456,8 +456,8 @@ class Bot(GroupMixin, discord.Client):
         lib = importlib.import_module(name)
         try:
             lib.setup(self)
-        except AttributeError:
+        except AttributeError as e:
-            raise discord.ClientException('extension does not have a setup function')
+            raise discord.ClientException('extension does not have a setup function') from e
 
         self.extensions[name] = lib
 

discord/ext/commands/core.py

@@ -183,8 +183,8 @@ class Command:
         elif converter is discord.Invite:
             try:
                 return bot.get_invite(argument.strip())
-            except:
+            except Exception as e:
-                raise BadArgument('Invite is invalid')
+                raise BadArgument('Invite is invalid') from e
 
     def _get_converter(self, param):
         converter = param.annotation
@@ -217,8 +217,8 @@ class Command:
             return self.do_conversion(ctx.bot, ctx.message, converter, argument)
         except CommandError as e:
             raise e
-        except Exception:
+        except Exception as e:
-            raise BadArgument('Converting to "{0.__name__}" failed.'.format(converter))
+            raise BadArgument('Converting to "{0.__name__}" failed.'.format(converter)) from e
 
     @property
     def clean_params(self):

discord/voice_client.py

@@ -400,7 +400,7 @@ class VoiceClient:
             p = subprocess.Popen(args, stdin=stdin, stdout=subprocess.PIPE)
             return ProcessPlayer(p, self, after)
         except subprocess.SubprocessError as e:
-            raise ClientException('Popen failed: {0.__name__} {1}'.format(type(e), str(e)))
+            raise ClientException('Popen failed: {0.__name__} {1}'.format(type(e), str(e))) from e
 
 
     def create_ytdl_player(self, url, *, options=None, use_avconv=False, after=None):