Fix race condition on shutdown

Closes #923

Quasar.Client/Networking/QuasarClient.cs

@@ -75,7 +75,15 @@ public void ConnectLoop()
 
                 while (Connected) // hold client open
                 {
-                    _token.WaitHandle.WaitOne(1000);
+                    try
+                    {
+                        _token.WaitHandle.WaitOne(1000);
+                    }
+                    catch (Exception e) when (e is NullReferenceException || e is ObjectDisposedException)
+                    {
+                        Disconnect();
+                        return;
+                    }
                 }
 
                 if (_token.IsCancellationRequested)

Quasar.Client/QuasarApplication.cs

@@ -104,13 +104,13 @@ public void Run()
         {
             // decrypt and verify the settings
             if (!Settings.Initialize())
-                Application.Exit();
+                Environment.Exit(1);
 
             ApplicationMutex = new SingleInstanceMutex(Settings.MUTEX);
 
             // check if process with same mutex is already running on system
             if (!ApplicationMutex.CreatedNew)
-                Application.Exit();
+                Environment.Exit(2);
 
             FileHelper.DeleteZoneIdentifier(Application.ExecutablePath);
 
@@ -124,7 +124,7 @@ public void Run()
                 try
                 {
                     installer.Install();
-                    Application.Exit();
+                    Environment.Exit(3);
                 }
                 catch (Exception e)
                 {
@@ -165,7 +165,7 @@ public void Run()
                     // Start connection loop on new thread and dispose application once client exits.
                     // This is required to keep the UI thread responsive and run the message loop.
                     _connectClient.ConnectLoop();
-                    Application.Exit();
+                    Environment.Exit(0);
                 }).Start();
             }
         }

Quasar.Client/User/ActivityDetection.cs

@@ -64,14 +64,14 @@ public void Start()
         /// </summary>
         private void UserActivityThread()
         {
-            while (!_token.WaitHandle.WaitOne(10))
+            try
             {
                 if (IsUserIdle())
                 {
                     if (_lastUserStatus != UserStatus.Idle)
                     {
                         _lastUserStatus = UserStatus.Idle;
-                        _client.Send(new SetUserStatus {Message = _lastUserStatus});
+                        _client.Send(new SetUserStatus { Message = _lastUserStatus });
                     }
                 }
                 else
@@ -79,10 +79,13 @@ private void UserActivityThread()
                     if (_lastUserStatus != UserStatus.Active)
                     {
                         _lastUserStatus = UserStatus.Active;
-                        _client.Send(new SetUserStatus {Message = _lastUserStatus});
+                        _client.Send(new SetUserStatus { Message = _lastUserStatus });
                     }
                 }
             }
+            catch (Exception e) when (e is NullReferenceException || e is ObjectDisposedException)
+            {
+            }
         }
 
         /// <summary>