Token remover: exit early if message already deleted

2 files changed, 22 insertions, 3 deletions

diff --git a/bot/cogs/token_remover.py b/bot/cogs/token_remover.py
index 1f7517501..ef979f222 100644
--- a/bot/cogs/token_remover.py
+++ b/bot/cogs/token_remover.py
@@ -4,7 +4,7 @@ import logging
 import re
 import typing as t
 
-from discord import Colour, Message
+from discord import Colour, Message, NotFound
 from discord.ext.commands import Cog
 
 from bot import utils
@@ -83,7 +83,13 @@ class TokenRemover(Cog):
     async def take_action(self, msg: Message, found_token: Token) -> None:
         """Remove the `msg` containing the `found_token` and send a mod log message."""
         self.mod_log.ignore(Event.message_delete, msg.id)
-        await msg.delete()
+
+        try:
+            await msg.delete()
+        except NotFound:
+            log.debug(f"Failed to remove token in message {msg.id}: message already deleted.")
+            return
+
         await msg.channel.send(DELETION_MESSAGE_TEMPLATE.format(mention=msg.author.mention))
 
         log_message = self.format_log_message(msg, found_token)
diff --git a/tests/bot/cogs/test_token_remover.py b/tests/bot/cogs/test_token_remover.py
index 98ea9f823..3349caa73 100644
--- a/tests/bot/cogs/test_token_remover.py
+++ b/tests/bot/cogs/test_token_remover.py
@@ -3,7 +3,7 @@ from re import Match
 from unittest import mock
 from unittest.mock import MagicMock
 
-from discord import Colour
+from discord import Colour, NotFound
 
 from bot import constants
 from bot.cogs import token_remover
@@ -282,6 +282,19 @@ class TokenRemoverTests(unittest.IsolatedAsyncioTestCase):
             channel_id=constants.Channels.mod_alerts
         )
 
+    @mock.patch.object(TokenRemover, "mod_log", new_callable=mock.PropertyMock)
+    async def test_take_action_delete_failure(self, mod_log_property):
+        """Shouldn't send any messages if the token message can't be deleted."""
+        cog = TokenRemover(self.bot)
+        mod_log_property.return_value = mock.create_autospec(ModLog, spec_set=True, instance=True)
+        self.msg.delete.side_effect = NotFound(MagicMock(), MagicMock())
+
+        token = mock.create_autospec(Token, spec_set=True, instance=True)
+        await cog.take_action(self.msg, token)
+
+        self.msg.delete.assert_called_once_with()
+        self.msg.channel.send.assert_not_awaited()
+
 
 class TokenRemoverExtensionTests(unittest.TestCase):
     """Tests for the token_remover extension."""