Remove most local error handlers & handle InChannelCheckFailure globally

* Add error handler to ignore InChannelCheckFailure in the verification
  cog
* Raise InChannelCheckFailure instead of MissingPermissions in !user
* Send message instead of raising BadArgument in !user to prevent help
  message from being shown in such case
* Clean up !user command

5 files changed, 30 insertions, 81 deletions

diff --git a/bot/cogs/error_handler.py b/bot/cogs/error_handler.py
index 033a49d39..cfcba6f26 100644
--- a/bot/cogs/error_handler.py
+++ b/bot/cogs/error_handler.py
@@ -18,6 +18,7 @@ from discord.ext.commands import Bot, Context
 
 from bot.api import ResponseCodeError
 from bot.constants import Channels
+from bot.decorators import InChannelCheckFailure
 
 log = logging.getLogger(__name__)
 
@@ -78,6 +79,8 @@ class ErrorHandler:
                 f"{ctx.message.author} is missing permissions to invoke command {command}: "
                 f"{e.missing_perms}"
             )
+        elif isinstance(e, InChannelCheckFailure):
+            await ctx.send(e)
         elif isinstance(e, (CheckFailure, CommandOnCooldown, DisabledCommand)):
             log.debug(
                 f"Command {command} invoked by {ctx.message.author} with error "
diff --git a/bot/cogs/information.py b/bot/cogs/information.py
index a2585f395..320750a24 100644
--- a/bot/cogs/information.py
+++ b/bot/cogs/information.py
@@ -1,16 +1,13 @@
 import logging
-import random
 import textwrap
 
 from discord import CategoryChannel, Colour, Embed, Member, TextChannel, VoiceChannel
-from discord.ext.commands import (
-    BadArgument, Bot, CommandError, Context, MissingPermissions, command
-)
+from discord.ext.commands import Bot, Context, command
 
 from bot.constants import (
-    Channels, Emojis, Keys, MODERATION_ROLES, NEGATIVE_REPLIES, STAFF_ROLES
+    Channels, Emojis, Keys, MODERATION_ROLES, STAFF_ROLES
 )
-from bot.decorators import with_role
+from bot.decorators import InChannelCheckFailure, with_role
 from bot.utils.checks import with_role_check
 from bot.utils.time import time_since
 
@@ -131,30 +128,25 @@ class Information:
         Returns info about a user.
         """
 
-        # Do a role check if this is being executed on
-        # someone other than the caller
-        if user and user != ctx.author:
-            if not with_role_check(ctx, *MODERATION_ROLES):
-                raise BadArgument("You do not have permission to use this command on users other than yourself.")
+        if user is None:
+            user = ctx.author
+
+        # Do a role check if this is being executed on someone other than the caller
+        if user != ctx.author and not with_role_check(ctx, *MODERATION_ROLES):
+            await ctx.send("You may not use this command on users other than yourself.")
+            return
 
-        # Non-moderators may only do this in #bot-commands and can't see
-        # hidden infractions.
+        # Non-moderators may only do this in #bot-commands and can't see hidden infractions.
         if not with_role_check(ctx, *STAFF_ROLES):
             if not ctx.channel.id == Channels.bot:
-                raise MissingPermissions("You can't do that here!")
+                raise InChannelCheckFailure(Channels.bot)
             # Hide hidden infractions for users without a moderation role
             hidden = False
 
-        # Validates hidden input
-        hidden = str(hidden)
-
-        if user is None:
-            user = ctx.author
-
         # User information
         created = time_since(user.created_at, max_units=3)
 
-        name = f"{user.name}#{user.discriminator}"
+        name = str(user)
         if user.nick:
             name = f"{user.nick} ({name})"
 
@@ -162,15 +154,13 @@ class Information:
         joined = time_since(user.joined_at, precision="days")
 
         # You're welcome, Volcyyyyyyyyyyyyyyyy
-        roles = ", ".join(
-            role.mention for role in user.roles if role.name != "@everyone"
-        )
+        roles = ", ".join(role.mention for role in user.roles if role.name != "@everyone")
 
         # Infractions
         infractions = await self.bot.api_client.get(
             'bot/infractions',
             params={
-                'hidden': hidden,
+                'hidden': str(hidden),
                 'user__id': str(user.id)
             }
         )
@@ -209,23 +199,6 @@ class Information:
 
         await ctx.send(embed=embed)
 
-    @user_info.error
-    async def user_info_command_error(self, ctx: Context, error: CommandError):
-        embed = Embed(colour=Colour.red())
-
-        if isinstance(error, BadArgument):
-            embed.title = random.choice(NEGATIVE_REPLIES)
-            embed.description = str(error)
-            await ctx.send(embed=embed)
-
-        elif isinstance(error, MissingPermissions):
-            embed.title = random.choice(NEGATIVE_REPLIES)
-            embed.description = f"Sorry, but you may only use this command within <#{Channels.bot}>."
-            await ctx.send(embed=embed)
-
-        else:
-            log.exception(f"Unhandled error: {error}")
-
 
 def setup(bot):
     bot.add_cog(Information(bot))
diff --git a/bot/cogs/snekbox.py b/bot/cogs/snekbox.py
index 05834e421..c8705ac6f 100644
--- a/bot/cogs/snekbox.py
+++ b/bot/cogs/snekbox.py
@@ -1,18 +1,14 @@
 import datetime
 import logging
-import random
 import re
 import textwrap
 from signal import Signals
 from typing import Optional, Tuple
 
-from discord import Colour, Embed
-from discord.ext.commands import (
-    Bot, CommandError, Context, NoPrivateMessage, command, guild_only
-)
+from discord.ext.commands import Bot, Context, command, guild_only
 
-from bot.constants import Channels, ERROR_REPLIES, NEGATIVE_REPLIES, STAFF_ROLES, URLs
-from bot.decorators import InChannelCheckFailure, in_channel
+from bot.constants import Channels, STAFF_ROLES, URLs
+from bot.decorators import in_channel
 from bot.utils.messages import wait_for_deletion
 
 
@@ -224,27 +220,6 @@ class Snekbox:
         finally:
             del self.jobs[ctx.author.id]
 
-    @eval_command.error
-    async def eval_command_error(self, ctx: Context, error: CommandError):
-        embed = Embed(colour=Colour.red())
-
-        if isinstance(error, NoPrivateMessage):
-            embed.title = random.choice(NEGATIVE_REPLIES)
-            embed.description = "You're not allowed to use this command in private messages."
-            await ctx.send(embed=embed)
-
-        elif isinstance(error, InChannelCheckFailure):
-            embed.title = random.choice(NEGATIVE_REPLIES)
-            embed.description = str(error)
-            await ctx.send(embed=embed)
-
-        else:
-            original_error = getattr(error, 'original', "no original error")
-            log.error(f"Unhandled error in snekbox eval: {error} ({original_error})")
-            embed.title = random.choice(ERROR_REPLIES)
-            embed.description = "Some unhandled error occurred. Sorry for that!"
-            await ctx.send(embed=embed)
-
 
 def setup(bot):
     bot.add_cog(Snekbox(bot))
diff --git a/bot/cogs/utils.py b/bot/cogs/utils.py
index 0c6d9d2ba..98208723a 100644
--- a/bot/cogs/utils.py
+++ b/bot/cogs/utils.py
@@ -1,5 +1,4 @@
 import logging
-import random
 import re
 import unicodedata
 from email.parser import HeaderParser
@@ -8,8 +7,8 @@ from io import StringIO
 from discord import Colour, Embed
 from discord.ext.commands import AutoShardedBot, Context, command
 
-from bot.constants import Channels, NEGATIVE_REPLIES, STAFF_ROLES
-from bot.decorators import InChannelCheckFailure, in_channel
+from bot.constants import Channels, STAFF_ROLES
+from bot.decorators import in_channel
 
 log = logging.getLogger(__name__)
 
@@ -133,13 +132,6 @@ class Utils:
 
         await ctx.send(embed=embed)
 
-    async def __error(self, ctx, error):
-        embed = Embed(colour=Colour.red())
-        if isinstance(error, InChannelCheckFailure):
-            embed.title = random.choice(NEGATIVE_REPLIES)
-            embed.description = str(error)
-            await ctx.send(embed=embed)
-
 
 def setup(bot):
     bot.add_cog(Utils(bot))
diff --git a/bot/cogs/verification.py b/bot/cogs/verification.py
index 56fcd63eb..6b42c9213 100644
--- a/bot/cogs/verification.py
+++ b/bot/cogs/verification.py
@@ -5,7 +5,7 @@ from discord.ext.commands import Bot, Context, command
 
 from bot.cogs.modlog import ModLog
 from bot.constants import Channels, Event, Roles
-from bot.decorators import in_channel, without_role
+from bot.decorators import InChannelCheckFailure, in_channel, without_role
 
 log = logging.getLogger(__name__)
 
@@ -152,6 +152,12 @@ class Verification:
         )
 
     @staticmethod
+    async def __error(ctx: Context, error):
+        if isinstance(error, InChannelCheckFailure):
+            # Do nothing; just ignore this error
+            error.handled = True
+
+    @staticmethod
     def __global_check(ctx: Context):
         """
         Block any command within the verification channel that is not !accept.