Allow configuration of XBE-24 keyboard layout

PamhagenSysCtrl/App.xaml.cs

@@ -34,6 +34,9 @@ namespace PamhagenSysCtrl {
         }
 
         protected override async void OnStartup(StartupEventArgs evt) {
+            if (Config == null)
+                return;
+
             Version = new Version(typeof(App).GetTypeInfo().Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion.Split('+')[0] ?? "0.0.0");
 
             Plant = new(Config.PlcPort);