bug#65987: 30.0.50; Packages without a maintainer Email address cannot be described

[Philip Kaludercic]

C-h P raises an error when the maintainer does not give an email
address.  For example, C-h P gtags-mode RET triggers this stack trace:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (wrong-type-argument listp "Jimmy Aguilar Mena")
  car("Jimmy Aguilar Mena")
  (if (car recipient) (progn (insert (car recipient))))
  package--print-email-button("Jimmy Aguilar Mena")
  (let ((maintainer (car tail))) (if (bolp) (progn (insert (make-string 13 
32)))) (package--print-email-button maintainer) (setq tail (cdr tail)))
  (while tail (let ((maintainer (car tail))) (if (bolp) (progn (insert 
(make-string 13 32)))) (package--print-email-button maintainer) (setq tail (cdr 
tail))))
  (let ((tail maintainers)) (while tail (let ((maintainer (car tail))) (if 
(bolp) (progn (insert (make-string 13 32)))) (package--print-email-button 
maintainer) (setq tail (cdr tail)))))
  (progn (if (proper-list-p maintainers) nil (setq maintainers (list 
maintainers))) (package--print-help-section (if (cdr maintainers) "Maintainers" 
"Maintainer")) (let ((tail maintainers)) (while tail (let ((maintainer (car 
tail))) (if (bolp) (progn (insert (make-string 13 32)))) 
(package--print-email-button maintainer) (setq tail (cdr tail))))))
  (if maintainers (progn (if (proper-list-p maintainers) nil (setq maintainers 
(list maintainers))) (package--print-help-section (if (cdr maintainers) 
"Maintainers" "Maintainer")) (let ((tail maintainers)) (while tail (let 
((maintainer (car tail))) (if (bolp) (progn (insert ...))) 
(package--print-email-button maintainer) (setq tail (cdr tail)))))))
  (let* ((desc (or (if (let* ... ...) pkg) (car (cdr ...)) (let (...) (if 
built-in ... ...)))) (name (if desc (let* (...) (progn ... ...)) pkg)) (pkg-dir 
(if desc (let* (...) (progn ... ...)))) (reqs (if desc (let* (...) (progn ... 
...)))) (required-by (if desc (package--used-elsewhere-p desc nil 'all))) 
(version (if desc (let* (...) (progn ... ...)))) (archive (if desc (let* (...) 
(progn ... ...)))) (extras (and desc (let* (...) (progn ... ...)))) (website 
(cdr (assoc :url extras))) (commit (cdr (assoc :commit extras))) (keywords (if 
desc (package-desc--keywords desc))) (built-in (eq pkg-dir 'builtin)) 
(installable (and archive (not built-in))) (status (if desc 
(package-desc-status desc) "orphan")) (incompatible-reason 
(package--incompatible-p desc)) (signed (if desc (let* (...) (progn ... ...)))) 
(maintainers (or (cdr (assoc :maintainers extras)) (cdr (assoc :maintainer 
extras)))) (authors (cdr (assoc :authors extras))) (news (let* ((pkg-dir ...) 
(s ...) (file ...) (s ...) (s ...)) (if s (progn file))))) (if (string= status 
"avail-obso") (progn (setq status "available obsolete"))) (if 
incompatible-reason (progn (setq status "incompatible"))) (princ (format 
"Package %S is %s.\n\n" name status)) (package--print-help-section "Status") 
(cond (built-in (insert (propertize (capitalize status) 'font-lock-face 
'package-status-built-in) ".")) (pkg-dir (insert (propertize (if ... 
"Installed" ...) 'font-lock-face 'package-status-built-in)) (insert 
(substitute-command-keys " in `")) (let ((dir ...)) (help-insert-xref-button 
dir 'help-package-def pkg-dir)) (if (and (package-built-in-p name) (not ...)) 
(insert (substitute-command-keys "',\n             shadowing a ") (propertize 
"built-in package" ... ...)) (insert (substitute-quotes "'"))) (if signed 
(insert ".") (insert " (unsigned).")) (if (and (let* ... ...) (not required-by) 
(member status ...)) (progn (insert " ") (package-make-button "Delete" ... ... 
... desc)))) (incompatible-reason (insert (propertize "Incompatible" 
'font-lock-face font-lock-warning-face) " because it depends on ") (if (stringp 
incompatible-reason) (insert "Emacs " incompatible-reason ".") (insert 
"uninstallable packages."))) (installable (insert (capitalize status)) (insert 
" from " (format "%s" archive)) (insert " -- ") (package-make-button "Install" 
'action 'package-install-button-action 'package-desc desc)) (t (insert 
(capitalize status) "."))) (insert "\n") (if (and pkg-dir (not archive)) nil 
(package--print-help-section "Archive" (or archive "n/a"))) (and version 
(package--print-help-section "Version" (package-version-join version))) (if 
commit (progn (package--print-help-section "Commit" commit))) (if desc (progn 
(package--print-help-section "Summary" (let* (...) (progn ... ...))))) (setq 
reqs (if desc (let* ((cl-x desc)) (progn (or ... ...) (aref cl-x 4))))) (if 
reqs (progn (package--print-help-section "Requires") (let ((first t)) (let 
(...) (while tail ...)) (insert "\n")))) (if required-by (progn 
(package--print-help-section "Required by") (let ((first t)) (let (...) (while 
tail ...)) (insert "\n")))) (if website (progn (if (string-match-p 
"^http://\\(?:\\(?:elpa\\|git\\|www\\)\\.\\)?\\..." website) (progn (let ... 
...))) (package--print-help-section "Website") (help-insert-xref-button website 
'help-url website) (insert "\n"))) (if keywords (progn 
(package--print-help-section "Keywords") (let ((tail keywords)) (while tail 
(let ... ... ... ...))) (insert "\n"))) (if maintainers (progn (if 
(proper-list-p maintainers) nil (setq maintainers (list maintainers))) 
(package--print-help-section (if (cdr maintainers) "Maintainers" "Maintainer")) 
(let ((tail maintainers)) (while tail (let ... ... ... ...))))) (if authors 
(progn (package--print-help-section (if (cdr authors) "Authors" "Author")) (let 
((tail authors)) (while tail (let ... ... ... ...))))) (let* ((all-pkgs (append 
(cdr ...) (cdr ...) (let ... ...))) (other-pkgs (delete desc all-pkgs))) (if 
other-pkgs (progn (package--print-help-section "Other versions" (mapconcat ... 
other-pkgs ", ") ".")))) (insert "\n") (let ((start-of-description (point))) 
(if built-in (insert (or (lm-commentary ...) "")) (if (package-installed-p 
desc) (insert (package--get-description desc)) (let* (... readme-string) 
(package--with-response-buffer-1 ... ... :file basename :async nil 
:error-function ... :noerror t) (insert ...)))) (if news (progn (insert "\n" 
(make-separator-line) "\n" (propertize "* News" ... ...) "\n\n") 
(insert-file-contents news))) (goto-char start-of-description) 
(package--describe-add-library-links) (goto-char start-of-description) 
(browse-url-add-buttons)))
  describe-package-1(gtags-mode)
  (save-current-buffer (set-buffer standard-output) (describe-package-1 
package))
  (closure ((package . gtags-mode)) nil (save-current-buffer (set-buffer 
standard-output) (describe-package-1 package)))()
  help--window-setup("*Help*" (closure ((package . gtags-mode)) nil 
(save-current-buffer (set-buffer standard-output) (describe-package-1 
package))))
  (if (not (or (let* ((cl-x package)) (progn (and (memq (type-of cl-x) 
cl-struct-package-desc-tags) t))) (and package (symbolp package)))) (message 
"No package specified") (help-setup-xref (list #'describe-package package) 
(called-interactively-p 'interactive)) (help--window-setup (help-buffer) 
#'(lambda nil (save-current-buffer (set-buffer standard-output) 
(describe-package-1 package)))))
  describe-package(gtags-mode)
  funcall-interactively(describe-package gtags-mode)
  command-execute(describe-package)
--8<---------------cut here---------------end--------------->8---

A simple solution would be

diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 02691ff7aa5..b784b0b0434 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -3089,6 +3090,8 @@ package--print-email-button
   "Insert a button whose action will send an email to RECIPIENT.
 NAME should have the form (FULLNAME . EMAIL) where FULLNAME is
 either a full name or nil, and EMAIL is a valid email address."
+  (when (stringp recipient)
+    (setq recipient (cons recipient "unknown@email.addr")))
   (when (car recipient)
     (insert (car recipient)))
   (when (and (car recipient) (cdr recipient))

or perhaps not render any button at all?


In GNU Emacs 30.0.50 (build 7, x86_64-pc-linux-gnu, GTK+ Version
 3.24.37, cairo version 1.16.0) of 2023-09-13 built on quetzal
Repository revision: a8959f1b245540a2d0d158621dedf244ac133849
Repository branch: master
System Description: Debian GNU/Linux 12 (bookworm)

Configured using:
 'configure --with-pgtk --with-native-compilation --with-imagemagick
 --with-tree-sitter'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ
IMAGEMAGICK JPEG JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PGTK PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XIM GTK3 ZLIB

Important settings:
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  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
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Major mode: ELisp/l

Minor modes in effect:
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Load-path shadows:
/home/philip/.config/emacs/site-lisp/company-coq/.auto-site hides 
~/.config/emacs/site-lisp/.auto-site
/home/philip/.config/emacs/site-lisp/flymake-proselint/flymake-proselint hides 
/home/philip/.config/emacs/elpa/flymake-proselint-0.3.0/flymake-proselint
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/home/philip/.config/emacs/elpa/vc-backup-1.1.0/vc-backup
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/home/philip/Source/emacs/lisp/transient
/home/philip/.config/emacs/elpa/sweeprolog/theme-loaddefs hides 
/home/philip/Source/emacs/lisp/theme-loaddefs
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