bug#43057: 28.0.50; icalendar makes Gnus signal an error

[Lars Ingebrigtsen]

Reading bug#37887, I got a backtrace, and it's down to this:

(gnus-icalendar-event-from-ical
 '((VCALENDAR nil
              ((PRODID nil "-//Google Inc//Google Calendar 70.9054//EN")
               (VERSION nil "2.0"))
              ((VEVENT nil
                       ((DTSTART nil "20200822T180000Z")
                        (DTEND nil "20200822T190000Z")
                        (DTSTAMP nil "20200825T203517Z")
                        (CREATED nil "20200822T180043Z")
                        (DESCRIPTION nil "To see detailed information for 
automatically crea...")
                        (LAST-MODIFIED nil "20200822T180043Z")
                        (SEQUENCE nil "0")
                        (SUMMARY nil "Reservation at Place"))
                       nil)))))

Results in the following backtrace:

Debugger entered--Lisp error: (invalid-slot-type gnus-icalendar-event uid str
  signal(invalid-slot-type (gnus-icalendar-event uid string nil))
  eieio--validate-slot-value(#s(eieio--class :name gnus-icalendar-event :docs
  eieio-oset(#<gnus-icalendar-event gnus-icalendar-event-156d24a9d7e0> uid ni
  #f(compiled-function (obj slots) "Set slots of OBJ with SLOTS which is a li
  apply(#f(compiled-function (obj slots) "Set slots of OBJ with SLOTS which i
  shared-initialize(#<gnus-icalendar-event gnus-icalendar-event-156d24a9d7e0>
  #f(compiled-function (this &optional slots) "Construct the new object THIS 
  apply(#f(compiled-function (this &optional slots) "Construct the new object
  initialize-instance(#<gnus-icalendar-event gnus-icalendar-event-156d24a9d7e
  #f(compiled-function (class &rest slots) "Default constructor for CLASS `ei
  apply(#f(compiled-function (class &rest slots) "Default constructor for CLA
  make-instance(gnus-icalendar-event :uid nil :recur nil :location nil :descr
  apply(make-instance gnus-icalendar-event (:uid nil :recur nil :location nil
  (let (--cl-map-property-- --cl-accumulate-args--) (setq --cl-map-property--
  (let* ((event (car (icalendar--all-events ical))) (organizer (replace-regex
  gnus-icalendar-event-from-ical(((VCALENDAR nil ((PRODID nil "-//Google Inc/





In GNU Emacs 28.0.50 (build 94, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, 
cairo version 1.16.0)
 of 2020-08-24 built on xo
Repository revision: 519fc10f121c59d6844afaf0ef0a1e1d67a2a934
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Debian GNU/Linux bullseye/sid


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