C# Covarinace and what has to do with Functional C#

.cs

using System;
using System.Threading.Tasks;

namespace FunctionalExperimentation.Practical.FuncTaskCovarinat
{
    public static partial class F
    {
        public static IFuncTask<T> ToWithResult<T>(this Func<Task<T>> @this) => new FuncTaskAdapter<T>(@this);
        public static T GetOrThrowIfNull<T>(this IFuncTask<T> @this, string message)
        {
            var value = @this.GetResult(); // this might also throw exception from Task. 
            return value ?? throw new Exception(message);
        }
        public static T GetOrThrow<T>(this IFuncTask<T> @this, string message)
        {
            try
            {
                return @this.GetOrThrowIfNull(message);
            }
            catch (Exception e) //Please Dont hide Exceptions
            {
                throw new Exception(message);
            }

        }

    }
    public interface IWithSuccess
    {
        public bool IsSuccessful { get; }
    }
    public class SomeResult : IWithSuccess
    {
        public bool IsSuccessful => true;
    }

    public class FuncTaskCovarinat
    {
        public static async Task RunAsync()
        {
            Func<Task<SomeResult>> GetSomethingLazyAsync() => () => Task.FromResult(new SomeResult());

            //Func<Task<IWithResult>> t = GetSomethingLazyAsync(); 
            //Error CS0029  Cannot implicitly convert type 'System.Func<System.Threading.Tasks.Task<FunctionalExperimentation.Practical.FuncTaskCovarinat.SomeResult>>'
            //    to 'System.Func<System.Threading.Tasks.Task<FunctionalExperimentation.Practical.FuncTaskCovarinat.IWithResult>>'

            //ok this is covariant on T
            IFuncTask<IWithSuccess> lazyResult = GetSomethingLazyAsync()
                                         .ToWithResult();

            SomeResult result = GetSomethingLazyAsync()
                                    .ToWithResult()
                                    .GetOrThrow("failed to get");
        }

        public static async Task RunAsyncClassic()
        {
            Func<Task<SomeResult>> GetSomethingLazyAsync() => () => Task.FromResult(new SomeResult());

            SomeResult result;

            var lazyTask = GetSomethingLazyAsync();
            result = await lazyTask();
            if (result is null)
                throw new Exception("failed to get Anything");

        }

        public static async Task RunAsyncClassicExtendedWithTryCatch()
        {
            Func<Task<SomeResult>> GetSomethingLazyAsync() => () => Task.FromResult(new SomeResult());

            SomeResult result;
            try
            {
                var lazyTask = GetSomethingLazyAsync();
                result = await lazyTask();
                if (result is null)
                    throw new Exception("failed to get Anything");
            }
            catch (Exception e) //Please Dont hide Exceptions
            {
                throw new Exception("failed to get Anything");
            }

        }

    }

    public interface IFuncTask<out T>
    {
        T GetResult();
    }
    public class FuncTaskAdapter<T> : IFuncTask<T>
    {
        public Func<Task<T>> Unwrap() => funcTask;
        private readonly Func<Task<T>> funcTask;
        public FuncTaskAdapter(Func<Task<T>> funcTask) =>
            this.funcTask = funcTask;
        public T GetResult() => funcTask().Result;

    }
}