bug#49866: 28.0.50; gnus-summary-exit from the transient search buffer giving error

["Basil L. Contovounesios" via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> Andy points out that the code above should not, by default, raise an
>> error if the `alist-get' call returns nil. Something in both Pankaj and
>> my installation has messed with the map functions so that this returns
>> an error:
>>
>> (map-merge 'list '(1 2 3) nil)
>>
>> I couldn't raise an error with "emacs -Q", instead it returned:
>>
>> ((1 . 2) (3))
>>
>> which also seems wrong, but at least isn't an error.
>
> Oh!
>
> I assumed that map-merge didn't work on nil arguments, too, but didn't
> actually check.  And indeed:
>
> (map-merge 'list nil nil)
> => nil
>
> So...  do you have an older version of map.el from ELPA/MELPA or
> something?

The problem isn't nil, it's '(1 2 3).  That is neither an alist, plist,
nor array, so what is map-merge meant to do with it?  Which are the keys
of the map, and which the values?  Note that a map type of 'list is a
synonym for 'alist.

-- 
Basil