I am not a subscriber.

In zsh --version:
zsh 5.0.8 (x86_64-apple-darwin15.0)

Iff there is an alias set on ls, then entering `ls\` followed by twice the
return key (i.e. the line break was accidental; the user just meant `ls`)
causes a segmentation fault.

In terminal, this looks likes like a Ctrl-d logout:
(`alias ls=ls -GFh` in zshrc)
% ls\
>
[Process completed]

In a fresh zsh -f we see why:
% alias ls=ls
% ls\
>
zsh: segmentation fault  zsh -f

Regards,
Ollie