Updated certain events to have more concrete event arguments. Added try-catch block around playlist save logic. Added DispatchQueue where necessary.

Harmonia.Core/Player/PlaylistChangedEventArgs.cs

@@ -0,0 +1,9 @@
+using Harmonia.Core.Playlists;
+
+namespace Harmonia.Core.Player;
+
+public class PlaylistChangedEventArgs(Playlist? oldPlaylist, Playlist? newPlaylist) : EventArgs
+{
+    public Playlist? OldPlaylist { get; } = oldPlaylist;
+    public Playlist? NewPlaylist { get; } = newPlaylist;
+}