bug#61639: 30.0.50; [PATCH] Do not error out on non image file in image-dired

[Eli Zaretskii <eliz@gnu.org>]

> From: Manuel Giraud <manuel@ledu-giraud.fr>
> Cc: 61639@debbugs.gnu.org
> Date: Mon, 20 Feb 2023 14:35:42 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Date: Sun, 19 Feb 2023 21:09:47 +0100
> >> From:  Manuel Giraud via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >> 
> >> This patch prevent errors when using image-dired on non image files.
> >
> > Why is it better to show a message than to signal an error?  The
> > former could go unnoticed, especially if some other message is shown
> > in the echo-area soon enough.
> 
> I don't think it is better.  But for some image-dired usage, I do not
> find it convenient.  Example: you carefully select some images from a
> dired buffer and hit `C-t d' to see them in image-dired.  But your
> selection was not correct and one of those file is not an image: you
> receive an error (and have to correct your selection) and don't get to
> see any of the correctly selected images.

So maybe "C-t d" should filter the selected "images" before it calls
the function which errors out?

IOW, if the application doesn't want an API to fail for reasons
specific to the application, the onus of avoiding the error is on the
application, no?