fix: DispatcherTimer leak in toast, delete-before-toast ordering in PostDraft

EbayListingTool/Views/SavedListingsView.xaml.cs

@@ -778,14 +778,14 @@ public partial class SavedListingsView : UserControl
             var draft = _selected.ToListingDraft();
             var url = await _ebayListing.PostListingAsync(draft);
 
-            ToastUrlText.Text = url;
-            ShowDraftPostedToast();
-
             var posted = _selected;
             _selected = null;
             _service?.Delete(posted);
             ClearDetail();
             RefreshList();
+
+            ToastUrlText.Text = url;
+            ShowDraftPostedToast();
         }
         catch (Exception ex)
         {
@@ -810,7 +810,11 @@ public partial class SavedListingsView : UserControl
 
     private void ShowDraftPostedToast()
     {
-        _toastTimer?.Stop();
+        if (_toastTimer != null)
+        {
+            _toastTimer.Stop();
+            _toastTimer = null;
+        }
         ToastTranslate.BeginAnimation(System.Windows.Media.TranslateTransform.YProperty, null);
         DraftPostedToast.Visibility = Visibility.Visible;
 
@@ -835,6 +839,7 @@ public partial class SavedListingsView : UserControl
     private void DismissToastAnimated()
     {
         _toastTimer?.Stop();
+        _toastTimer = null;
         var slideOut = new System.Windows.Media.Animation.DoubleAnimation(
             0, 60, new Duration(TimeSpan.FromMilliseconds(180)))
         {