NSubstitute: Stack Empty exception

gistfile1.cs

Bug or am i doing something stupid? Want to pretend that the first call to menu.PrintMenu() in GetSelection never happened by clearing received calls from the sub itself.

    [TestFixture]
    public class NSubBug
    {
        public interface IMenu
        {
            void PrintMenu();
            string GetUserSelection();
        }

        public void GetSelection(IMenu menu)
        {
            menu.PrintMenu();
            var userSelection = menu.GetUserSelection();
            if (userSelection == "m")
            {
                menu.PrintMenu();
            }
        }

        [Test]
        public void WhenUserSelectsPrintMenu()
        {
            var menu = Substitute.For<IMenu>();
            menu.When(x => x.GetUserSelection()).Do(c => menu.ClearReceivedCalls());
            menu.GetUserSelection().Returns("m");

            GetSelection(menu);

            menu.Received().PrintMenu(); //Expect only called once
        }
    }

==== Results in:

System.InvalidOperationException : Stack empty.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.Stack`1.Pop()
   at NSubstitute.Core.CallStack.Pop()
   at NSubstitute.Core.ResultSetter.SetResultForLastCall(IReturn valueToReturn, MatchArgs matchArgs)
   at NSubstitute.Core.CallRouter.LastCallShouldReturn(IReturn returnValue, MatchArgs matchArgs)
   at NSubstitute.Core.SubstitutionContext.LastCallShouldReturn(IReturn value, MatchArgs matchArgs)
   at NSubstitute.SubstituteExtensions.Returns[T](MatchArgs matchArgs, T returnThis, T[] returnThese)
   at NSubstitute.SubstituteExtensions.Returns[T](T value, T returnThis, T[] returnThese)
   at PuzzleGame.GameTests.MakeUserSelection(String menuOption) in c:\Users\Administrator\AppData\Local\NCrunch\3752\3\Game.cs:line 134
   at PuzzleGame.GameTests.WhenUserSelectsPrintMenu() in c:\Users\Administrator\AppData\Local\NCrunch\3752\3\Game.cs:line 112