Better exception for using viewCell with collection View (#25681)

src/Controls/src/Core/Handlers/Items/Android/TemplatedItemViewHolder.cs

@@ -57,7 +57,13 @@ namespace Microsoft.Maui.Controls.Handlers.Items
 				_itemContentView.Recycle();
 
 				// Create the new content
-				View = (View)template.CreateContent();
+				var content = template.CreateContent();
+				View = content as View;
+
+				if(View is null)
+				{
+					throw new InvalidOperationException($"{template} could not be created from {content}");
+				}
 
 				// Set the binding context _before_ we create the renderer; that way, the bound data will be 
 				// available during OnElementChanged

src/Controls/src/Core/Handlers/Items/iOS/TemplatedCell.cs

@@ -168,7 +168,12 @@ namespace Microsoft.Maui.Controls.Handlers.Items
 				}
 
 				// Create the content and renderer for the view 
-				var view = itemTemplate.CreateContent() as View;
+				var content = itemTemplate.CreateContent();
+
+				if(content is not View view)
+				{
+					throw new InvalidOperationException($"{itemTemplate} could not be created from {content}");
+				}
 
 				// Set the binding context _before_ we create the renderer; that way, it's available during OnElementChanged
 				view.BindingContext = bindingContext;

src/Controls/src/Core/Platform/Windows/CollectionView/ItemContentControl.cs

@@ -172,7 +172,14 @@ namespace Microsoft.Maui.Controls.Platform
 				// If the content has never been realized (i.e., this is a new instance), 
 				// or if we need to switch DataTemplates (because this instance is being recycled)
 				// then we'll need to create the content from the template 
-				_visualElement = dataTemplate.CreateContent() as VisualElement;
+				var content = dataTemplate.CreateContent();
+				_visualElement = content as VisualElement;
+
+				if(_visualElement is null)
+				{
+					throw new InvalidOperationException($"{dataTemplate} could not be created from {content}");
+				}
+
 				_visualElement.BindingContext = dataContext;
 				_handler = _visualElement.ToHandler(mauiContext);