This has an effect on find-file-hook for totally unrelated files,
through the callchain of `org-roam-db-autosync--setup-file-h ->
org-roam-file-p -> org-roam-descendant-of-p'.

From an org file, inside a project-el project, (find-file
"some/other/file") will intermittently reproduce this error:

   org-roam-descendant-of-p: Wrong type argument: arrayp, nil

If this fix seems inappropriate -- it could amount to surppressing a
valid error in routine calls -- then I would advise throwing an
explicit signal here, or finding a safer way to get the `path` inside
`org-roam-file-p'; the current means:

    (or file (buffer-file-name (buffer-base-buffer)))

.. can result in nil, which then bleeds errors into use elsewhere.

for posterity, here is the full calling context I'm referring to, from
`org-roam-file-p'.

  (let* ((path (or file (buffer-file-name (buffer-base-buffer))))
         (ext (when path (org-roam--file-name-extension path)))
         (ext (if (string= ext "gpg")
                  (org-roam--file-name-extension (file-name-sans-extension path))
                ext))
         (org-roam-dir-p (org-roam-descendant-of-p path
         org-roam-directory))
         ...