Hi,

In some folder, e.g. "/tmp":
1. Create folder named "news"
2. emacs -Q
3. M-x list-packages
4. RET on any available not installed package

This will produce "Read error: Is a directory, /tmp/news" message.

In GNU Emacs 29.0.50
Repository revision: 2772ebe3667f28cefd0d6134204ce6a3c7a8c323
Repository branch: master

Adding news to package description was introuced in
dd98fedd0c7f27bfba046d761042c19181cb461d

Adding Philip to Cc as the author of the original commit.

Attached patch solves issue by checking that:
1. pkg-dir is not nil
2. pkg-dir is not 'builtin
3. "news" is a regular file