ref TStringArray garr = {"A", "B", "C"};

void TestArr(TStringArray arr, bool recursive = true)
{
    Print("[1] " + (arr != null));
    if (recursive)
        TestArr(null, false);
    Print("[2] " + (arr != null));
}

> TesTarr(garr)
[1] true  // Non-null argument passed in
[1] false  // Expected, recursive call with null argument
[2] false  // Expected, recursive call with null argument
[2] false  // back in caller, passed in arg now null despite it shouldn't be