Added Requested Changes.

Author: SubhikshaSf4851

src/Controls/src/Core/Handlers/Shell/ShellHandler.Windows.cs

@@ -129,6 +129,7 @@ public static void MapFlyoutBackground(ShellHandler handler, Shell view)
 					view.FlyoutBackgroundColor?.AsPaint());
 		}
 
+		//TODO: Make it public in .NET 10.
 		internal static void MapFlyoutBackgroundImage(ShellHandler handler, Shell view)
 		{
 			var provider = handler.GetRequiredService<IImageSourceServiceProvider>();

src/Core/src/Platform/Windows/NavigationViewExtensions.cs

@@ -270,6 +270,12 @@ internal static async Task UpdateBackgroundImageSourceAsync(this MauiNavigationV
 
 			var service = provider.GetRequiredImageSourceService(imageSource);
 			var nativeImageSource = await service.GetImageSourceAsync(imageSource);
+			
+			if (nativeImageSource is null)
+			{
+				paneContentGrid.Background = null;
+				return;
+			}
 
 			var BackgroundImage = new ImageBrush
 			{