slamhound.el calls just-one-space w/ a negative argument to also delete newlines around point. This feature of just-one-space was added in Emacs 24, so slamhound.el cannot be used with older Emacsen.
This is somewhat unfortunate given that Emacs 24 hasn't been released yet.
add Emacs version requirement
I should add that calling just-one-space w/ a negative argument in Emacs 23 deletes all spaces. This is why slamhound.el cannot be used w/ older Emacsen.
Good catch; thanks.