[RFC PATCH v5 10/18] discord: Add error handler on events

[Muhammad Rizki <kiizuha@gnuweeb.org>]

Add an error handler to ignore the `CommandNotFound` error while someone
sends a message with the bot prefix (e.g `$hai`) that is not exist in
the bot basic commands. Actually, this error wouldn't appear if set
log_handler to None in the main file on the client.run() parameter.
But I will keep this if using a log handler in the future use.

The error log says:
discord.ext.commands.bot: Ignoring exception in command None
discord.ext.commands.errors.CommandNotFound: Command "w" is not found

Signed-off-by: Muhammad Rizki <kiizuha@gnuweeb.org>
---
 .../dscord/gnuweeb/plugins/events/__init__.py   |  2 ++
 .../dscord/gnuweeb/plugins/events/on_error.py   | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 daemon/dscord/gnuweeb/plugins/events/on_error.py

diff --git a/daemon/dscord/gnuweeb/plugins/events/__init__.py b/daemon/dscord/gnuweeb/plugins/events/__init__.py
index d9a891f..7074e4d 100644
--- a/daemon/dscord/gnuweeb/plugins/events/__init__.py
+++ b/daemon/dscord/gnuweeb/plugins/events/__init__.py
@@ -4,8 +4,10 @@
 #
 
 from .on_ready import OnReady
+from .on_error import OnError
 
 
 class Events(
 	OnReady,
+	OnError
 ): pass
diff --git a/daemon/dscord/gnuweeb/plugins/events/on_error.py b/daemon/dscord/gnuweeb/plugins/events/on_error.py
new file mode 100644
index 0000000..e1e4e28
--- /dev/null
+++ b/daemon/dscord/gnuweeb/plugins/events/on_error.py
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright (C) 2022  Muhammad Rizki <kiizuha@gnuweeb.org>
+#
+
+from discord.ext import commands
+
+
+class OnError(commands.Cog):
+	def __init__(self, bot: "commands.Bot") -> None:
+		self.bot = bot
+
+
+	@commands.Cog.listener()
+	async def on_command_error(self, _, err):
+		if isinstance(err, commands.CommandNotFound):
+			pass
-- 
Muhammad Rizki