Code compiles and run in another window, yet bombs out here with a big error code. Where's the issue?

I'm running one of your 'Finals' and it's bombing out for; System.ArgumentNullException: Value cannot be null. Parameter name: String at System.Number.StringToNumber (System.String str, NumberStyles options, System.NumberBuffer& number, System.Globalization.NumberFormatInfo info, Boolean parseDecimal) <0x7f6605fdea10 + 0x000ff> in <filename unknown>:0 at System.Number.ParseInt32 (System.String s, NumberStyles style, System.Globalization.NumberFormatInfo info) <0x7f6605fdd120 + 0x00094> in <filename unknown>:0 at System.Int32.Parse (System.String s) <0x7f6605fbe4a0 + 0x0001d> in <filename unknown>:0 at Treehouse.CodeChallenges.Program.Main () <0x4181dc50 + 0x00058> in <filename unknown>:0 at MonoTester.Run () [0x000d5] in /workdir/MonoTester.cs:93

The program runs in my workspaces window as requested. Program name is Test.cs.

I'd like to move on to the next section but if I'm not getting something, I'd like to be squared away first.

using System;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main()
        {
            while(true)
            {
                    Console.Write("Enter the number of times to print \"Yay!\": ");
                    string input = Console.ReadLine();                

                try 
                {
                    int count = int.Parse(input);

                    int i = 0;
                    while(i < count)
                    {
                        i += 1;   
                        Console.WriteLine("Yay!");
                    }
                }

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