From 8f04fd436f70e591e21a54345885c13137089c2c Mon Sep 17 00:00:00 2001
From: Flame442 <34169552+Flame442@users.noreply.github.com>
Date: Mon, 20 Jan 2020 14:09:17 -0800
Subject: [PATCH] Catches `discord.NotFound` in `utils.mod.mass_purge` (#3414)

* Catches `discord.NotFound` in `mass_purge`

* Create 3378.bugfix.rst
---
 changelog.d/3378.bugfix.rst |  1 +
 redbot/core/utils/mod.py    | 11 ++++++-----
 2 files changed, 7 insertions(+), 5 deletions(-)
 create mode 100644 changelog.d/3378.bugfix.rst

diff --git a/changelog.d/3378.bugfix.rst b/changelog.d/3378.bugfix.rst
new file mode 100644
index 000000000..caff4e2ef
--- /dev/null
+++ b/changelog.d/3378.bugfix.rst
@@ -0,0 +1 @@
+Fixed an error when ``redbot.core.utils.mod.mass_purge`` is passed ``COUNT % 100 == 1`` messages AND the last message in the list does not exist.
diff --git a/redbot/core/utils/mod.py b/redbot/core/utils/mod.py
index 030eaa3ba..2b5b1df10 100644
--- a/redbot/core/utils/mod.py
+++ b/redbot/core/utils/mod.py
@@ -38,12 +38,13 @@ async def mass_purge(messages: List[discord.Message], channel: discord.TextChann
 
     """
     while messages:
-        if len(messages) > 1:
+        # discord.NotFound can be raised when `len(messages) == 1` and the message does not exist.
+        # As a result of this obscure behavior, this error needs to be caught just in case.
+        try:
             await channel.delete_messages(messages[:100])
-            messages = messages[100:]
-        else:
-            await messages[0].delete()
-            messages = []
+        except discord.errors.HTTPException:
+            pass
+        messages = messages[100:]
         await asyncio.sleep(1.5)