From 816b0bdf9feec17c3431b67708f5d226e0214ed3 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Fri, 21 Jul 2023 22:48:12 +0200
Subject: [PATCH] Fix _get_thumb failed when document had no thumbs

---
 telethon/client/downloads.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/telethon/client/downloads.py b/telethon/client/downloads.py
index d7ae5a9c..3a1d4685 100644
--- a/telethon/client/downloads.py
+++ b/telethon/client/downloads.py
@@ -741,6 +741,9 @@ class DownloadMethods:
 
     @staticmethod
     def _get_thumb(thumbs, thumb):
+        if not thumbs:
+            return None
+
         # Seems Telegram has changed the order and put `PhotoStrippedSize`
         # last while this is the smallest (layer 116). Ensure we have the
         # sizes sorted correctly with a custom function.