Dispatcher: QuickMenu: Fix footgun

Fixes: #9594

frontend/dispatcher.lua

@@ -851,7 +851,8 @@ function Dispatcher:addSubMenu(caller, menu, location, settings)
             and location[settings].settings.show_as_quickmenu
         end,
         callback = function()
-            if location[settings] and location[settings].settings then
+            if location[settings] then
+                if location[settings].settings then
                     if location[settings].settings.show_as_quickmenu then
                         location[settings].settings.show_as_quickmenu = nil
                         if next(location[settings].settings) == nil then
@@ -864,6 +865,7 @@ function Dispatcher:addSubMenu(caller, menu, location, settings)
                     location[settings].settings = {["show_as_quickmenu"] = true}
                 end
                 caller.updated = true
+            end
         end,
     })
     table.insert(menu, {