Fixed loading multiple songs issue.

Harmonia.Core/Player/AudioPlayer.cs

@@ -9,6 +9,8 @@ public class AudioPlayer : IAudioPlayer
     private readonly IAudioEngine _audioEngine;
     private readonly IPlaylistManager _playlistManager;
 
+    private int _loadVersion;
+
     private Playlist? _playlist;
     public Playlist? Playlist
     {
@@ -241,8 +243,15 @@ public class AudioPlayer : IAudioPlayer
 
         CurrentPlaylistSong = song;
 
+        int loadVersion = Interlocked.Increment(ref _loadVersion);
+
         bool isLoaded = await TryLoadAsync(song);
 
+        // A newer load request was started while this one was in flight;
+        // abandon this one so only the latest request controls playback.
+        if (loadVersion != Volatile.Read(ref _loadVersion))
+            return false;
+
         if (isLoaded == false)
         {
             if (mode == PlaybackMode.LoadAndPlay)