bug#15721: 24.3; Error in post-command-hook (flyspell-post-command-hook): (wrong-type-argument integer-or-marker-p nil)

[Leo Liu]

I got this from time to time:

        Error in post-command-hook (flyspell-post-command-hook):
        (wrong-type-argument integer-or-marker-p nil)

But I don't know how to reproduce it reliably. So I put in this form

      (unless (numberp flyspell-pre-point)
                (message "DEBUG-flyspell-pre-point: %S" flyspell-pre-point))

before (goto-char flyspell-pre-point) in flyspell-post-command-hook.

This is what is in *Messages* when the error happened:
DEBUG-flyspell-pre-point: nil

So it seems flyspell-post-command-hook needs to check current buffer is
flyspell-pre-buffer. But I am not totally sure.

Leo