I get this error message:'System.ArgumentNullException: Value cannot be null. Parameter name: String. See output for sta

using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            bool notCorrectInput = true;
            int numberTimes;
            while (notCorrectInput)
            {
                try
                {
                    Console.Write("Enter the number of times to print \"Yay!\": ");
                    string numTimes = Console.ReadLine();
                    numberTimes = int.Parse(numTimes);
                    int counter = 0;
                    while (counter < numberTimes)
                    {
                        Console.WriteLine("\"Yay!\"");
                        counter += 1;
                    }

                }
                catch (FormatException)
                {
                    Console.WriteLine("You must enter a whole number.");
                    continue;
                }
                notCorrectInput = false;
            }
        }
    }
}