Remove chance of lowering a none

bin/launch

@@ -165,7 +165,8 @@ class SwayWin(Window):
         # For wayland windows, the app id is the class, but for
         # xwayland windows, the app_id is None and there is a class
         # set.
-        self.wm_class = swaywin.app_id or swaywin.window_class.lower()
+        self.wm_class = swaywin.app_id or swaywin.window_class or ""
+        self.wm_class = self.wm_class.lower()
 
     def get_desktop(self)->Optional[str]:
         "In sway, desktops get names, not numbers"