bug#49341: 28.0.50; bookmark--unfontify with nil filename throws wrong-type error

[Eli Zaretskii]

> Date: Fri, 02 Jul 2021 21:08:06 +0000
> From: Trey Peacock <gpg@treypeacock.com>
> 
> I am unable to use `bookmark-delete` with bookmarks that do not return
> alist values for 'filename or 'position when called with
> `bookmark-get-bookmark`.

Can you show a recipe for reproducing the problem, please?

> I believe it is due to the May 4th commit
> ab6cb65cb2b6d11a7b690dfcea8d98611290fad9 where bookmark--unfontify
> was introduced. The unfontify function is unable to handle nil
> values for these fields and results in calling `(overlay-at pos)`
> which shows a wrong-type error.

Boruch, could you please take a look?

Thanks.