Fix missing default in server ups

exp_legacy/module/modules/gui/server-ups.lua

@@ -36,7 +36,7 @@ UsesServerUps:on_load(function(player_name, visible)
     local label = player.gui.screen[server_ups.name]
     --- @diagnostic disable-next-line undefined-field
     if not External.valid() or not storage.ext.var.server_ups then visible = false end
-    label.visible = visible
+    label.visible = visible or false
 end)
 
 --- Toggles if the server ups is visbile