bug#38310: 27.0.50; (image-convert "data" t) doesn't work

[Lars Ingebrigtsen]

Katsumi Yamaoka <yamaoka@jpl.org> writes:

> Ah, thanks.  I verified both these tests work with Emacs -Q.
>
> (with-current-buffer
>     (url-retrieve-synchronously
>      "https://www.gstatic.com/webp/gallery/1.sm.webp";)
>   (goto-char (point-min))
>   (search-forward "\n\n")
>   (image-convert (buffer-substring (point) (point-max)) 'image/webp))

Perhaps image-convert should signal an explicit error if the second
parameter isn't on the proper format?

I've now added some better error feedback on the trunk.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no