using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        IList<string> strList1 = new List<string>()

        {"Two", "Three", "Four", "Five"};

        IList<string> strList2 = new List<string>()

        {null, "Two", "Three", "Four", "Five"};

        Console.WriteLine(strList1.LastOrDefault(s => s.Contains("T")));

        Console.WriteLine(strList2.LastOrDefault(s => s.Contains("T"))); // throws an exception

    }

}