Add an error handler to the discord bot (#235)

* add error handler for the bot

discord-bot/bot/bot.py

@@ -1,11 +1,14 @@
 # -*- coding: utf-8 -*-
 """Bot logic."""
+from datetime import datetime
+
 import aiosqlite
 import hikari
 import lightbulb
 import miru
 from bot.api_client import OasstApiClient
 from bot.settings import Settings
+from bot.utils import EMPTY, mention
 
 settings = Settings()
 
@@ -38,3 +41,77 @@ async def on_stopping(event: hikari.StoppingEvent):
     """Cleanup."""
     await bot.d.db.close()
     await bot.d.oasst_api.close()
+
+
+async def _send_error_embed(
+    content: str, exception: lightbulb.errors.LightbulbError | BaseException, ctx: lightbulb.Context
+) -> None:
+    ctx.command
+    embed = hikari.Embed(
+        title=f"`{exception.__class__.__name__}` Error{f' in `{ctx.command.name}`' if ctx.command else '' }",
+        description=content,
+        color=0xFF0000,
+        timestamp=datetime.now().astimezone(),
+    ).set_author(name=ctx.author.username, url=str(ctx.author.avatar_url))
+
+    await ctx.respond(EMPTY, embed=embed)
+
+
+@bot.listen(lightbulb.CommandErrorEvent)
+async def on_error(event: lightbulb.CommandErrorEvent) -> None:
+    """Error handler for the bot."""
+    # Unwrap the exception to get the original cause
+    exc = event.exception.__cause__ or event.exception
+    ctx = event.context
+
+    if isinstance(event.exception, lightbulb.CommandInvocationError):
+        if not event.context.command:
+            await _send_error_embed("Something went wrong", exc, ctx)
+        else:
+            await _send_error_embed(
+                f"Something went wrong during invocation of command `{event.context.command.name}`.", exc, ctx
+            )
+
+        raise event.exception
+
+    # Not an owner
+    if isinstance(exc, lightbulb.NotOwner):
+        await _send_error_embed("You are not the owner of this bot.", exc, ctx)
+    # Command is on cooldown
+    elif isinstance(exc, lightbulb.CommandIsOnCooldown):
+        await _send_error_embed(f"This command is on cooldown. Retry in `{exc.retry_after:.2f}` seconds.", exc, ctx)
+    # Missing permissions
+    elif isinstance(exc, lightbulb.errors.MissingRequiredPermission):
+        await _send_error_embed(
+            f"You do not have permission to use this command. Missing permissions: {exc.missing_perms}", exc, ctx
+        )
+    # Missing roles
+    elif isinstance(exc, lightbulb.errors.MissingRequiredRole):
+        assert event.context.guild_id is not None  # Roles only exist in guilds
+        await _send_error_embed(
+            f"You do not have the correct role to use this command. Missing role(s): {[mention(r, 'role') for r in exc.missing_roles]}",
+            exc,
+            ctx,
+        )
+    # Only a guild command
+    elif isinstance(exc, lightbulb.errors.OnlyInGuild):
+        await _send_error_embed("This command can only be run in servers.", exc, ctx)
+    # Only a DM command
+    elif isinstance(exc, lightbulb.errors.OnlyInDM):
+        await _send_error_embed("This command can only be run in DMs.", exc, ctx)
+    # Not enough arguments
+    elif isinstance(exc, lightbulb.errors.NotEnoughArguments):
+        await _send_error_embed(
+            f"Not enough arguments were supplied to the command. {[opt.name for opt in exc.missing_options]}", exc, ctx
+        )
+    # Bot missing permission
+    elif isinstance(exc, lightbulb.errors.BotMissingRequiredPermission):
+        await _send_error_embed(
+            f"The bot does not have the correct permission(s) to execute this command. Missing permissions: {exc.missing_perms}",
+            exc,
+            ctx,
+        )
+    elif isinstance(exc, lightbulb.errors.MissingRequiredAttachment):
+        await _send_error_embed("Not enough attachemnts were supplied to this command.", exc, ctx)
+    else:
+        raise exc