Akka async continuations

Program.cs

using Akka.Actor;
using Akka.Dispatch;
using System.Diagnostics;

var actorSystem = ActorSystem.Create("ActorSystem");
actorSystem.ActorOf(Props.Create(() => new SupervisorActor()));
Console.ReadKey();

class SupervisorActor : ReceiveActor
{
    private IActorRef _childActor;

    public SupervisorActor()
    {
        _childActor = Context.ActorOf(Props.Create(() => new ChildActor()));
        Context.Watch(_childActor);
        Receive<Terminated>(
             c => c.ActorRef == _childActor, t => {
                 Debug.WriteLine("Child actor terminated");
        });
        Task.Run(async () =>
        {
            await Task.Delay(2000);
            _childActor.Tell(PoisonPill.Instance);
            //await _childActor.GracefulStop(TimeSpan.FromSeconds(10));
            Debug.WriteLine("GracefulStop returned");
        });
    }

}

class ChildActor: ReceiveActor
{
    protected override void PostStop()
    {
        async Task DisposeThing()
        {
            Debug.WriteLine("Before Delay");
            await Task.Delay(1); // This would be the actual call to dispose the thing
            Debug.WriteLine("After Delay");
        };

        ActorTaskScheduler.RunTask(async () =>
        {
            try
            {
                Debug.WriteLine("Before Wait");
                await DisposeThing();
                Debug.WriteLine("After Wait");
            }
            catch (Exception ex)
            {
                Debug.WriteLine($"An exception occured: {ex}");
            }
            finally
            {
                Debug.WriteLine("actor done disposing.");
            }
        });
    }
}