using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        List<ReceiptResponse> MyList = null;

        var t1 = MyList?[0]?.FileName;      

        Console.WriteLine("pass#1");

        var t2 = MyList?.FirstOrDefault()?.FileName;

        Console.WriteLine("pass#2");

        Console.Write(t1 ?? "t1 null", t2 ?? "t2 null");

​

    }

    public class ReceiptResponse

    {    

        public string FileName { get; set; }

        public string ContentType { get; set; }

        public Guid FacilityId { get; set; }

        public Guid PatientID { get; set; }

    }

}