Fixed empty cell tooltip

inabox.wpf/DynamicGrid/Columns/DynamicImageColumn.cs

@@ -1,10 +1,14 @@
+using System.Drawing;
 using System.Windows.Media.Imaging;
 using InABox.Core;
+using InABox.WPF;
 
 namespace InABox.DynamicGrid;
 
 public class DynamicImageColumn : DynamicActionColumn
 {
+    private static readonly BitmapImage empty = new Bitmap(32, 32).ToBitmapImage();
+
     public delegate BitmapImage? GetImageDelegate(CoreRow? row);
 
     public DynamicImageColumn(GetImageDelegate image, ActionDelegate? action = null)
@@ -25,5 +29,5 @@ public class DynamicImageColumn : DynamicActionColumn
 
     public bool AllowHeaderClick { get; set; } = false;
         
-    public override object? Data(CoreRow? row) => Image?.Invoke(row);
+    public override object? Data(CoreRow? row) => Image?.Invoke(row) ?? empty;
 }