segfault when deleting attributes or items

[Christopher Armstrong]

Lunatic segfaults when deleting attributes of LuaObjects. I noticed this when experimenting with deleting globals to restrict what my lua environment can do.

>>> import lua; globs = lua.globals()
>>> del globs.io
zsh: segmentation fault python

>>> import lua; lua.execute("x = {a = 3}")
>>> del lua.eval("x")["a"]
zsh: segmentation fault python

[Jonathan Jacobs (jjacobs)]

This would appear to be caused by not handling the value == NULL case in LuaObject_setattr.