What I expected was:
Also tested in compiled app, with same (non-crashing) behavior. Any insight? Anyone? Anyone? Bueller?
David Owens writes:
@ericasadun maybe it's debugDescription() was updated to not crash on nil? Not sure when that changed.
— David Owens II (@owensd) July 17, 2015
And finally, word of Jordan:
@ericasadun I think the book is just being a bit imprecise. It's safe to work with the IUO (including printing), just not the value inside.
— Jordan Rose (@UINT_MIN) July 17, 2015