Fix for checking result before processing next iteration:

Retrieving-all-dialogs.md

@@ -21,8 +21,8 @@ while True:
     dialogs.extend(result.dialogs)
     users.extend(result.users)
     chats.extend(result.chats)
-    last_date = min(msg.date for msg in result.messages)
-    if not result.dialogs:
+    if not result.messages:
         break
+    last_date = min(msg.date for msg in result.messages)
     sleep(2)
 ```