[listview] fixes for various null/empty DataTemplate

src/Compatibility/Core/src/Android/VisualElementRenderer.cs

@@ -300,10 +300,10 @@ protected virtual void OnElementPropertyChanged(object sender, PropertyChangedEv
 
 		protected override void OnLayout(bool changed, int l, int t, int r, int b)
 		{
-			if (Element == null)
-				return;
-
-			UpdateLayout(((IElementController)Element).LogicalChildren);
+			if (Element is IElementController controller)
+			{
+				UpdateLayout(controller.LogicalChildren);
+			}
 		}
 
 		public override void Draw(Canvas canvas)

src/Controls/src/Core/TemplatedItemsList.cs

@@ -534,8 +534,14 @@ public DataTemplate SelectDataTemplate(object item)
 
 		public TItem ActivateContent(int index, object item)
 		{
-			TItem content = ItemTemplate != null ? (TItem)ItemTemplate.CreateContent(item, _itemsView) : _itemsView.CreateDefault(item);
-
+			if (ItemTemplate?.CreateContent(item, _itemsView) is TItem content)
+			{
+				// content is valid
+			}
+			else
+			{
+				content = _itemsView.CreateDefault(item);
+			}
 			content = UpdateContent(content, index, item);
 
 			return content;

src/Controls/tests/DeviceTests/Elements/ListView/ListViewTests.cs

@@ -20,6 +20,7 @@ void SetupBuilder()
 				builder.ConfigureMauiHandlers(handlers =>
 				{
 					handlers.AddHandler<ViewCell, ViewCellRenderer>();
+					handlers.AddHandler<TextCell, TextCellRenderer>();
 					handlers.AddHandler<ListView, ListViewRenderer>();
 					handlers.AddHandler<VerticalStackLayout, LayoutHandler>();
 					handlers.AddHandler<Label, LabelHandler>();
@@ -152,5 +153,61 @@ await CreateHandlerAndAddToWindow<LayoutHandler>(layout, async (handler) =>
 				await Task.Delay(100);
 			});
 		}
+
+		[Fact]
+		public async Task NullTemplateDoesntCrash()
+		{
+			SetupBuilder();
+			ObservableCollection<string> data = new ObservableCollection<string>()
+			{
+				"cat",
+				"dog",
+				"catdog"
+			};
+
+			var listView = new ListView(ListViewCachingStrategy.RecycleElement)
+			{
+				ItemTemplate = new DataTemplate(() =>
+				{
+					return new ViewCell
+					{
+						View = new VerticalStackLayout
+						{
+							new Label()
+						}
+					};
+				}),
+				ItemsSource = data
+			};
+
+			var layout = new VerticalStackLayout
+			{
+				listView
+			};
+
+			await CreateHandlerAndAddToWindow<LayoutHandler>(layout, async _ =>
+			{
+				await Task.Delay(100);
+				ValidatePlatformCells(listView);
+			});
+
+			// Default ctor
+			listView.ItemTemplate = new DataTemplate();
+
+			await CreateHandlerAndAddToWindow<LayoutHandler>(layout, async _ =>
+			{
+				await Task.Delay(100);
+				ValidatePlatformCells(listView);
+			});
+
+			// Return null
+			listView.ItemTemplate = new DataTemplate(() => null);
+
+			await CreateHandlerAndAddToWindow<LayoutHandler>(layout, async _ =>
+			{
+				await Task.Delay(100);
+				ValidatePlatformCells(listView);
+			});
+		}
 	}
 }