[Xotcl] Segfault after undefining "new" proc in a class namespace

[Arthur Schreiber]

Hey Gustaf,

The following is propably a very uncommon use case, but it causes a
segfault, so I think it's rather serious:

% package require nx
% nx::Class create A {}
% proc ::A::new {} { return "something" }
% A new
something
% rename ::A::new ""
% A new
[1]    2515 segmentation fault (core dumped)  tclsh

Kind regards,
Arthur