UI: Prevent null ldn game model arrays from entering the SetEntries method

src/Ryujinx/UI/ViewModels/LdnGamesListViewModel.cs

@@ -177,6 +177,8 @@ namespace Ryujinx.Ava.UI.ViewModels
 
         private void SetEntries(IEnumerable<LdnGameModel> entries)
         {
+            entries ??= [];
+
             _visibleEntries = entries.ToList();
             OnPropertyChanged(nameof(VisibleEntries));
         }

src/Ryujinx/UI/ViewModels/MainWindowViewModel.cs

@@ -149,7 +149,7 @@ namespace Ryujinx.Ava.UI.ViewModels
         /// </summary>
         public SafeDictionary<string, LdnGameModel.Array> UsableLdnData = [];
 
-        private LdnGameModel[] _ldnModels;
+        private LdnGameModel[] _ldnModels = [];
 
         public LdnGameModel[] LdnModels
         {