Apply fix from #12114 to AppCompat

Author: jfversluis

Xamarin.Forms.Platform.Android/AppCompat/Platform.cs

@@ -184,9 +184,13 @@ public static SizeRequest GetNativeSize(VisualElement view, double widthConstrai
 		{
 			Performance.Start(out string reference);
 
-			// FIXME: potential crash
 			IVisualElementRenderer visualElementRenderer = Android.Platform.GetRenderer(view);
 
+			if (visualElementRenderer == null || visualElementRenderer.View.IsDisposed())
+			{
+				return new SizeRequest(Size.Zero, Size.Zero);
+			}
+
 			var context = visualElementRenderer.View.Context;
 
 			// negative numbers have special meanings to android they don't to us