App Crash On Load

[End3r6]

Whenever I try to load and play a file, my app crashes and I get a null reference exception. This is my code:

        ISimpleAudioPlayer player;
        public void OnPlay()
        {
            player = CrossSimpleAudioPlayer.CreateSimpleAudioPlayer();
            player.Load(GetStreamFromFile("Make Me Glow.mp3"));
            player.Play();
        }

        Stream? GetStreamFromFile(string filename)
        {
            var assembly = typeof(App).GetTypeInfo().Assembly;
            var stream = assembly.GetManifestResourceStream("TestMVVM." + filename);
            return stream;
        }

        public void OnPause()
        {
            player.Pause();
        }

        public void OnResume()
        {
            player.Play();
        }

        public void OnStop()
        {
            player.Stop();
        }

I would guess this has something to do with me using Avalonia UI, I just wanted to make sure that I wasn't missing something. Any help would be greatly appreciated. :)