norm_datetime handles None

rocketbot/utils.py

@@ -209,6 +209,8 @@ def format_bytes(size: int) -> str:
 def norm_datetime(dt: datetime) -> datetime:
 	"""Converts a datetime to UTC for consistent comparison."""
 	# "Naive" datetimes (without a time zone) are assumed as system local time zone
+	if dt is None:
+		return dt
 	return datetime.fromtimestamp(dt.timestamp(), timezone.utc)
 
 MOD_PERMISSIONS: Permissions = Permissions(Permissions.manage_messages.flag)