Fixed a lot of "in the wild" problems.

Katteker.Gui/UserInterface.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Linq;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Forms;
@@ -13,7 +12,6 @@ namespace Katteker
     public static class UserInterface
     {
         private static UpdateManager _manager;
-        private static Action _restartApp;
 
         /// <summary>
         ///     Checks for Updates.
@@ -40,8 +38,7 @@ namespace Katteker
             }
 
             var releases = (await _manager.CheckForUpdateAsync().ConfigureAwait(false)).ToArray();
-            _restartApp = () => _manager.RestartApp();
-            if (releases.Any() || !isStartup)
+            if (releases.Length > 0 || !isStartup)
             {
                 var thread = new Thread(ThreadProcess);
                 thread.SetApartmentState(ApartmentState.STA);
@@ -58,7 +55,7 @@ namespace Katteker
                 var dialogResult = window.ShowDialog();
                 if (dialogResult == DialogResult.OK)
                 {
-                    _restartApp?.Invoke();
+                    _manager.RestartApp();
                 }
             }
         }