bug#25735: 26.0.50; url-retrieve errors are peculiar

[Richard Copley <rcopley@gmail.com>]

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On Wed, 15 May 2019 at 08:46, Lars Ingebrigtsen <larsi@gnus.org> wrote:

> (Sorry for sending the previous email several times; I had some problems
> with the MTA...)
>
> I've now changed the doc string to
>
> ---
>
> \(:redirect REDIRECTED-TO) - the request was redirected to this URL.
>
> \(:error (error type . DATA)) - an error occurred.  TYPE is a
> symbol that says something about where the error occurred, and
> DATA is a list (possibly nil) that describes the error further.


If there's a way to use that data to format an error message,
it would be good to provide an example, or a "see info node X",
if it's a common idiom.

I think usually if you're looking at a docstring it's because you
want to know how to use the function (as well as what it is for
and what exactly it does, which I think are covered in this case).

This is what I ended up with, after I reported the bug.
Sadly I didn't make a note of where if anywhere I cribbed it from.

(url-retrieve URL
              (lambda (status cbargs)
                (cl-loop for (key value) on status by 'cddr
                         do (when (eq key :error) (error "%s: %s" (car
value) (cdr value))))
                BODY))

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