taking a reference of an alias of an undefined array value, ...

The fact that they are aliases, nor that the array elements are undefined, seems to have no bearing upon the 'problem' at all:

Of course; it's just memory reuse, but I just listed all the facts... ,-)

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}