chore: Avoid NRE

src/Uno.UI/UI/Xaml/Controls/Image/Image.Android.cs

@@ -132,7 +132,7 @@ namespace Windows.UI.Xaml.Controls
 
 			_imageFetchDisposable.Disposable = null;
 
-			if (imageSource != null && imageSource.UseTargetSize)
+			if (imageSource is not null && imageSource.UseTargetSize)
 			{
 				// If the ImageSource has the UseTargetSize set, the image
 				// must not be loaded until the first layout has been done.
@@ -146,7 +146,7 @@ namespace Windows.UI.Xaml.Controls
 				}
 			}
 
-			if (imageSource.ResourceFailed)
+			if (imageSource?.ResourceFailed == true)
 			{
 				// Currently resource-based images are evaluated immediately
 				// in the constructor - so we have to raise ImageFailed late.