Simple Error Handling for ext.commands - discord.py

error_handler.py

import traceback
import sys
from discord.ext import commands
import discord

"""
If you are not using this inside a cog, add the event decorator e.g:
@bot.event
async def on_command_error(ctx, error)

For examples of cogs see:
Rewrite:
https://gist.github.com/EvieePy/d78c061a4798ae81be9825468fe146be
Async:
https://gist.github.com/leovoel/46cd89ed6a8f41fd09c5

This example uses @rewrite version of the lib. For the async version of the lib, simply swap the places of ctx, and error.
e.g: on_command_error(self, error, ctx)

For a list of exceptions:
http://discordpy.readthedocs.io/en/rewrite/ext/commands/api.html#errors
"""

@commands.Cog.listener()
class CommandErrorHandler(commands.Cog):
    def __init__(self, bot):
        self.bot = bot

    async def on_command_error(self, ctx, error):
        """The event triggered when an error is raised while invoking a command.
        ctx   : Context
        error : Exception"""

        # This prevents any commands with local handlers being handled here in on_command_error.
        if hasattr(ctx.command, 'on_error'):
            return
        
        ignored = (commands.CommandNotFound, commands.UserInputError)
        
        # Allows us to check for original exceptions raised and sent to CommandInvokeError.
        # If nothing is found. We keep the exception passed to on_command_error.
        error = getattr(error, 'original', error)
        
        # Anything in ignored will return and prevent anything happening.
        if isinstance(error, ignored):
            return

        elif isinstance(error, commands.DisabledCommand):
            return await ctx.send(f'{ctx.command} has been disabled.')

        elif isinstance(error, commands.NoPrivateMessage):
            try:
                return await ctx.author.send(f'{ctx.command} can not be used in Private Messages.')
            except:
                pass

        # For this error example we check to see where it came from...
        elif isinstance(error, commands.BadArgument):
            if ctx.command.qualified_name == 'tag list':  # Check if the command being invoked is 'tag list'
                return await ctx.send('I could not find that member. Please try again.')

        # All other Errors not returned come here... And we can just print the default TraceBack.
        print('Ignoring exception in command {}:'.format(ctx.command), file=sys.stderr)
        traceback.print_exception(type(error), error, error.__traceback__, file=sys.stderr)
    
    """Below is an example of a Local Error Handler for our command do_repeat"""
    @commands.command(name='repeat', aliases=['mimic', 'copy'])
    async def do_repeat(self, ctx, *, inp: str):
        """A simple command which repeats your input!
        inp  : The input to be repeated"""

        await ctx.send(inp)

    @do_repeat.error
    async def do_repeat_handler(self, ctx, error):
        """A local Error Handler for our command do_repeat.
        This will only listen for errors in do_repeat.

        The global on_command_error will still be invoked after."""

        # Check if our required argument inp is missing.
        if isinstance(error, commands.MissingRequiredArgument):
            if error.param.name == 'inp':
                await ctx.send("You forgot to give me input to repeat!")
                

def setup(bot):
    bot.add_cog(CommandErrorHandler(bot))

error_handler_clean.py

import traceback
import sys
from discord.ext import commands
import discord

@commands.Cog.listener()
class CommandErrorHandler(commands.Cog):
    def __init__(self, bot):
        self.bot = bot

    async def on_command_error(self, ctx, error):
        """The event triggered when an error is raised while invoking a command.
        ctx   : Context
        error : Exception"""

        if hasattr(ctx.command, 'on_error'):
            return
        
        ignored = (commands.CommandNotFound, commands.UserInputError)
        error = getattr(error, 'original', error)
        
        if isinstance(error, ignored):
            return

        elif isinstance(error, commands.DisabledCommand):
            return await ctx.send(f'{ctx.command} has been disabled.')

        elif isinstance(error, commands.NoPrivateMessage):
            try:
                return await ctx.author.send(f'{ctx.command} can not be used in Private Messages.')
            except:
                pass

        elif isinstance(error, commands.BadArgument):
            if ctx.command.qualified_name == 'tag list':
                return await ctx.send('I could not find that member. Please try again.')
            
        print('Ignoring exception in command {}:'.format(ctx.command), file=sys.stderr)
        traceback.print_exception(type(error), error, error.__traceback__, file=sys.stderr)
    
    @commands.command(name='repeat', aliases=['mimic', 'copy'])
    async def do_repeat(self, ctx, *, inp: str):
        await ctx.send(inp)

    @do_repeat.error
    async def do_repeat_handler(self, ctx, error):
        if isinstance(error, commands.MissingRequiredArgument):
            if error.param.name == 'inp':
                await ctx.send("You forgot to give me input to repeat!")
                

def setup(bot):
    bot.add_cog(CommandErrorHandler(bot))