CmdPal: try to fix the context menu crash, again. (#40814)

Cherry-pick of 782ee47. That is probably over-aggressive, but it fixes
it.

Closes  #40633
previously: #40744

---------

Co-authored-by: Yu Leng (from Dev Box) <yuleng@microsoft.com>

src/modules/cmdpal/Microsoft.CmdPal.UI/Converters/ContextItemTemplateSelector.cs

@@ -33,9 +33,14 @@ internal sealed partial class ContextItemTemplateSelector : DataTemplateSelector
                 li.AllowFocusOnInteraction = false;
                 dataTemplate = Separator;
             }
+            else if (item is CommandContextItemViewModel commandItem)
+            {
+                dataTemplate = commandItem.IsCritical ? Critical : Default;
+            }
             else
             {
-                dataTemplate = ((CommandContextItemViewModel)item).IsCritical ? Critical : Default;
+                // Fallback for unknown types
+                dataTemplate = Default;
             }
         }