CmdPal: Add null check before caching view model for item (#45815)

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/ListViewModel.cs

@@ -227,6 +227,13 @@ public partial class ListViewModel : PageViewModel, IDisposable
             var reused = 0;
             foreach (var item in newItems)
             {
+                try
+                {
+                    if (item is null)
+                    {
+                        continue;
+                    }
+
                     // Check for cancellation during item processing
                     if (cancellationToken.IsCancellationRequested)
                     {
@@ -255,6 +262,11 @@ public partial class ListViewModel : PageViewModel, IDisposable
                         created++;
                     }
                 }
+                catch (Exception ex)
+                {
+                    CoreLogger.LogError("Failed to load item:\n", ex + ToString());
+                }
+            }
 
 #if DEBUG
             CoreLogger.LogInfo($"[ListViewModel] FetchItems: {created} created, {reused} reused, {_vmCache.Count} cached");