Avoid another MemoryError

tests/telethon/test_utils.py

@@ -1,6 +1,8 @@
 import io
 import pathlib
 
+import pytest
+
 from telethon import utils
 from telethon.tl.types import (
     MessageMediaGame, Game, PhotoEmpty

tests/telethon/tl/test_serialization.py

@@ -0,0 +1,13 @@
+import pytest
+
+from telethon.tl import types, functions
+
+
+def test_nested_invalid_serialization():
+    large_long = 2**62
+    request = functions.account.SetPrivacyRequest(
+        key=types.InputPrivacyKeyChatInvite(),
+        rules=[types.InputPrivacyValueDisallowUsers(users=[large_long])]
+    )
+    with pytest.raises(TypeError):
+        bytes(request)