[O] can't schedule/deadline items with no existing schedule/deadline?

[Eric Abrahamsen]

The fact that no one else has reported this makes me think it's user
error, but I can reproduce with emacs -Q, so here goes:

Scheduling or deadlining an item with no existing SCHEDULE/DEADLINE
errors out, because both call code like this:

(let* ((old-date (org-entry-get nil "SCHEDULED"))
       (old-date-time (org-time-string-to-time old-date))

If there's no old-date, then "nil" gets fed to
`org-time-string-to-time', which doesn't accept "nil".

I adventured into git looking to see if something had changed recently
regarding org-time-string-to-time, and it doesn't seem to have, which
makes me all the more suspicious that I'm doing something wrong. But it
still won't work with emacs -Q, so...

What am I doing wrong?

Thanks,
Eric