Since upgrading to emacs 29.1 org-cite-insert no longer copes with 
bibliography files in json format where there is an entry for a book 
that has only editors and no author.

Expected behaviour:
Running org-cite-insert opens the bibliography file and allows me to 
search for a citation and insert it in the org file I’m editing.

Actual behaviour:
Running org-cite-insert fails to open the bibliography file with the 
following error:

org-cite-basic--key-completion-table: Wrong type argument: stringp, 
(((family . "Asimov") (given . "Isaac")) ((family . "Greenberg") (given 
. "Martin H.")))

(The exact error alters depending on the contents of the entry it fails on.)

Reproducing:
Attached are two bibliography files, citation-test-only-editor.json and 
citation-test-author.json, the first of which has a single entry of a 
book with two editors and no author, the second has the same book but 
I’ve changed one editor to an author.  Create an org file with 
“#+bibliography: citation-test-only-editor.json” or “#+bibliography: 
citation-test-author.json” at the top, and try running org-cite-insert.

Notes:
- The problem persists with emacs -Q.
- It is not a problem if I export my bibliography as a .bib file, just 
when it’s a .json file.
- It worked as I expected in emacs 28.2.
- Other parts of using org-cite seem to be unaffected but I haven’t 
exhaustively tested – I have just noted that manually typing in the 
citation and exporting the org file with a #+print_bibliography: line 
worked as expected and fontifying manually entered citations with 
org-cite-csl-activate works as expected.

Best wishes,
Margaret Patterson.

Emacs  : GNU Emacs 29.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 
3.24.20, cairo version 1.16.0)
  of 2023-08-04
Package: Org mode version 9.6.6 (release_9.6.6 @ 
/snap/emacs/current/usr/share/emacs/29.1/lisp/org/)