Crashes on "generic bomb"

[WhiteBlackGoose]

Code to repro:

using System;

Console.WriteLine(Hmh<int, string>(10));

static string Hmh<T, U>(int r)
{
    if (r == 0)
        return typeof(T).AssemblyQualifiedName;
    return Hmh<(T, U), (U, T)>(r - 1);
}