I'm running it fine in the Workspace but it's not working in the Assessment: System.NullReferenceException error.

using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            while (true)
            {
                Console.Write("Enter the number of times to print \"Yay!\": ");
                var entry = Console.ReadLine();
                if (entry.ToLower() == "quit")
                {
                    Console.WriteLine("Goodbye!");
                    break;
                }
                else
                {
                  try
                  {
                    int count = int.Parse(entry);
                    if (count <= 0)
                    {
                      Console.WriteLine("You must enter a positive number");
                    }
                    else if (count > 0)
                    {
                    int n = 1;
                    while (n <= count)
                      {
                          Console.WriteLine("Yay!");
                          n++;
                      }
                    }
                  }
                  catch (FormatException)
                  {
                    Console.WriteLine("You must enter a valid number");
                  }
                }
            }
        }
    }
}