Fix control catalog crash

samples/ControlCatalog/Pages/PointersPage.xaml.cs

@@ -59,7 +59,7 @@ Position: ??? ???";
             e.Pointer.Capture(null);
             e.Handled = true;
         }
-        else
+        else if (e.Pointer.Captured is not null)
         {
             throw new InvalidOperationException("How?");
         }