bug#68514: 30.0.50; minibuffer-choose-completion + elisp-c-a-p delete next sexp when completing after open paren

[Stefan Monnier]

> Incidentally, are these (point-max) checks necessary?  We're not doing
> anything that can cause us to leave the narrowed region, I think.

`char-after` returns nil at EOB, which would cause an error in `char-syntax`.


        Stefan