Fixed: don't edit when nothing selected on listbox

Windows/Forms/EditTileFolderForm.cs

@@ -312,6 +312,11 @@ namespace FizzyLauncher.Windows.Forms
                 return;
             }
 
+            if (listBox1.ListBox.SelectedIndex < 0)
+            {
+                return;
+            }
+
             EditTileForm.ShowEditDialog(listBox1);
         }