Steve Purcell <steve@sanityinc.com> wrote:
> Given an init.el snippet like:
>
>     (add-hook 'after-init-hook
>               (lambda ()
>                 (require 'server)
>                 (unless (server-running-p)
>                   (server-start))))
>
> the `load-history' var will contain an entry with a nil car (as per its
> documentation), inside which the `(require . server)' load will be
> noted.
>
> However, the code in `package--list-loaded-files' unconditionally
> applies `file-name-sans-extension' to the cars of `load-history',
> resulting in errors whenever packages are activated (e.g. upgraded,
> installed).
>
> I believe the correct fix would be simply add a `stringp' test here:
>
> https://github.com/emacs-mirror/emacs/blob/5abaf16ab49b86ca5add981c2ddcaea6db0c8a08/lisp/emacs-lisp/package.el#L759
>
> (Using a nightly Emacs HEAD snapshot from a couple of days ago.)

This is actually not limited to package.el.  E. g. lisp/help-fns.el was also written in assumtion, that cars of elements of ‘load-history’ are always file names: