Log errors in Discord channels

didier/cogs/discord.py

@@ -49,6 +49,12 @@ class Discord(commands.Cog):
             await birthdays.add_birthday(session, ctx.author.id, date)
             await self.client.confirm_message(ctx.message)
 
+    @commands.command(name="Join", usage="[Thread]")
+    async def join(self, ctx: commands.Context, thread: discord.Thread):
+        """Make Didier join a thread"""
+        if thread.me is not None:
+            return await ctx.reply()
+
 
 async def setup(client: Didier):
     """Load the cog"""

didier/cogs/owner.py

@@ -43,7 +43,7 @@ class Owner(commands.Cog):
         return await self.client.is_owner(ctx.author)
 
     @commands.command(name="Error", aliases=["Raise"])
-    async def _error(self, ctx: commands.Context, message: str = "Debug"):
+    async def _error(self, ctx: commands.Context, *, message: str = "Debug"):
         """Raise an exception for debugging purposes"""
         raise Exception(message)
 

didier/data/embeds/error_embed.py

@@ -0,0 +1,47 @@
+import traceback
+
+import discord
+from discord.ext import commands
+
+from didier.utils.discord.constants import Limits
+from didier.utils.types.string import abbreviate
+
+__all__ = ["create_error_embed"]
+
+
+def _get_traceback(exception: Exception) -> str:
+    """Get a proper representation of the exception"""
+    tb = traceback.format_exception(type(exception), exception, exception.__traceback__)
+    error_string = ""
+    for line in tb:
+        # Don't add endless tracebacks
+        if line.strip().startswith("The above exception was the direct cause of"):
+            break
+
+        # Escape Discord markdown formatting
+        error_string += line.replace(r"*", r"\*").replace(r"_", r"\_")
+        if line.strip():
+            error_string += "\n"
+
+    return abbreviate(error_string, Limits.EMBED_FIELD_VALUE_LENGTH)
+
+
+def create_error_embed(ctx: commands.Context, exception: Exception) -> discord.Embed:
+    """Create an embed for the traceback of an exception"""
+    description = _get_traceback(exception)
+
+    if ctx.guild is None:
+        origin = "DM"
+    else:
+        origin = f"{ctx.channel.mention} ({ctx.guild.name})"
+
+    invocation = f"{ctx.author.display_name} in {origin}"
+
+    embed = discord.Embed(colour=discord.Colour.red())
+    embed.set_author(name="Error")
+    embed.add_field(name="Command", value=f"{ctx.message.content}", inline=True)
+    embed.add_field(name="Context", value=invocation, inline=True)
+    embed.add_field(name="Exception", value=abbreviate(str(exception), Limits.EMBED_FIELD_VALUE_LENGTH), inline=False)
+    embed.add_field(name="Traceback", value=description, inline=False)
+
+    return embed

didier/didier.py

@@ -10,6 +10,7 @@ import settings
 from database.crud import custom_commands
 from database.engine import DBSession
 from database.utils.caches import CacheManager
+from didier.data.embeds.error_embed import create_error_embed
 from didier.utils.discord.prefix import get_prefix
 
 __all__ = ["Didier"]
@@ -139,6 +140,9 @@ class Didier(commands.Bot):
 
         await self.process_commands(message)
 
+        # TODO easter eggs
+        # TODO stats
+
     async def _try_invoke_custom_command(self, message: discord.Message) -> bool:
         """Check if the message tries to invoke a custom command
 
@@ -162,11 +166,50 @@ class Didier(commands.Bot):
         # Nothing found
         return False
 
-    async def on_command_error(self, context: commands.Context, exception: commands.CommandError, /) -> None:
+    async def on_thread_create(self, thread: discord.Thread):
-        """Event triggered when a regular command errors"""
+        """Event triggered when a new thread is created"""
-        # Print everything to the logs/stderr
+        await thread.join()
-        await super().on_command_error(context, exception)
 
-        # If developing, do nothing special
+    async def on_command_error(self, ctx: commands.Context, exception: commands.CommandError, /):
+        """Event triggered when a regular command errors"""
+        # If working locally, print everything to your console
         if settings.SANDBOX:
+            await super().on_command_error(ctx, exception)
             return
+
+        # If commands have their own error handler, let it handle the error instead
+        if hasattr(ctx.command, "on_error"):
+            return
+
+        # Ignore exceptions that aren't important
+        if isinstance(
+            exception,
+            (
+                commands.CommandNotFound,
+                commands.CheckFailure,
+                commands.TooManyArguments,
+            ),
+        ):
+            return
+
+        # Print everything that we care about to the logs/stderr
+        await super().on_command_error(ctx, exception)
+
+        if isinstance(exception, commands.MessageNotFound):
+            return await ctx.reply("This message could not be found.", ephemeral=True, delete_after=10)
+
+        if isinstance(
+            exception,
+            (
+                commands.BadArgument,
+                commands.MissingRequiredArgument,
+                commands.UnexpectedQuoteError,
+                commands.ExpectedClosingQuoteError,
+            ),
+        ):
+            return await ctx.reply("Invalid arguments.", ephemeral=True, delete_after=10)
+
+        if settings.ERRORS_CHANNEL is not None:
+            embed = create_error_embed(ctx, exception)
+            channel = self.get_channel(settings.ERRORS_CHANNEL)
+            await channel.send(embed=embed)

readme.md

@@ -61,3 +61,5 @@ black
 flake8
 mypy
 ```
+
+It's also convenient to have code-formatting happen automatically on-save. The [`Black documentation`](https://black.readthedocs.io/en/stable/integrations/editors.html) explains how to set this up for different types of editors.