ApplicationEntryPoint.cs

using System.Threading.Tasks;
using UniRx;
using UniRx.Async;
using UnityEngine;

namespace Minamo.Client.Core
{
    public class ApplicationEntryPoint
    {
        private static UniTaskCompletionSource _source = new UniTaskCompletionSource();
        public static UniTask WaitInitializationAsync() => _source.Task;

        [RuntimeInitializeOnLoadMethod]
        private static void Main()
        {
            MainCoreAsync().ConfigureAwait(PlayerLoopTiming.Update).Forget();
        }

        private static UniTask MainCoreAsync()
        {
            MessagePack.Resolvers.CompositeResolver.RegisterAndSetAsDefault
            (
                MessagePack.Resolvers.GeneratedResolver.Instance,
                MessagePack.Resolvers.BuiltinResolver.Instance,
                MessagePack.Resolvers.PrimitiveObjectResolver.Instance,
                Resolvers.MagicOnionResolver.Instance
            );

            _source.TrySetResult();

            return UniTask.CompletedTask;
        }
    }
}