Move progress bar animation init to Loaded event to fix possible null exception of ProgressBar

Flow.Launcher/MainWindow.xaml

@@ -342,6 +342,7 @@
                     Margin="12 0 12 0"
                     HorizontalAlignment="Center"
                     VerticalAlignment="Bottom"
+                    Loaded="ProgressBar_Loaded"
                     StrokeThickness="2"
                     Visibility="{Binding ProgressBarVisibility, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                     X1="-100"

Flow.Launcher/MainWindow.xaml.cs

@@ -26,7 +26,7 @@
 using Flow.Launcher.Plugin.SharedModels;
 using Flow.Launcher.ViewModel;
 using iNKORE.UI.WPF.Modern;
 using iNKORE.UI.WPF.Modern.Controls;
 using DataObject = System.Windows.DataObject;
 using Key = System.Windows.Input.Key;
 using MouseButtons = System.Windows.Forms.MouseButtons;
@@ -116,7 +116,7 @@
         {
             var handle = Win32Helper.GetWindowHandle(this, true);
             _hwndSource = HwndSource.FromHwnd(handle);
             _hwndSource.AddHook(WndProc);
             Win32Helper.HideFromAltTab(this);
             Win32Helper.DisableControlBox(this);
         }
@@ -199,9 +199,6 @@
                 ThemeManager.Current.ApplicationTheme = ApplicationTheme.Dark;
             }
 
-            // Initialize position
-            InitProgressbarAnimation();
-
             // Force update position
             UpdatePosition();
 
@@ -354,6 +351,11 @@
             }
         }
 
+        private void ProgressBar_Loaded(object sender, RoutedEventArgs e)
+        {
+            InitProgressbarAnimation();
+        }
+
         private async void OnClosing(object sender, CancelEventArgs e)
         {
             if (!CanClose)
@@ -374,7 +376,7 @@
         {
             try
             {
                 _hwndSource.RemoveHook(WndProc);
             }
             catch (Exception)
             {
@@ -587,9 +589,9 @@
 
         #endregion
 
         #region Window WndProc
 
         private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled) 
         {
             switch (msg)
             {
@@ -813,17 +815,17 @@
                 Header = Localize.iconTrayOpen() + " (" + _settings.Hotkey + ")",
                 Icon = openIcon
             };
             var gamemodeIcon = new FontIcon { Glyph = "\ue7fc" };
             var gamemode = new MenuItem
             {
                 Header = Localize.GameMode(),
                 Icon = gamemodeIcon
             };
             var positionresetIcon = new FontIcon { Glyph = "\ue73f" };
             var positionreset = new MenuItem
             {
                 Header = Localize.PositionReset(),
                 Icon = positionresetIcon
             };
             var settingsIcon = new FontIcon { Glyph = "\ue713" };
             var settings = new MenuItem