Hey, I just found this and this might be what I'm desperately looking for. I just finally managed to set up org-cite and bibtex-actions and I'm so delighted that (almost) everything works so nicely now, but I keep getting errors via the default csl export (to all output formats):

citeproc-bt--to-csl-date: Wrong type argument: stringp, nil

I already converted my biblatex bib-file to bibtex, but it's still not working. I'm using Zotero. If I reduce my pretty large file to one example entry, it works. So there must be something csl doesn't like about some of my entries, but I can't diagnose what that might be.

Am I right to assume that this patched version might help with this?

Here's my lousy attempt configuring things, in case you're interested. I'm using Doom Emacs and the biblio module, but I wasn't sure how things work so probably there's some duplication.

*** =oc=

#+begin_src elisp
(use-package! oc)
#+end_src

*** =citeproc=

#+begin_src elisp :tangle packages.el
(package! citeproc)
#+end_src

*** =oc-csl=

#+begin_src elisp
(use-package! oc-csl)
#+end_src

*** =oc-biblatex=

#+begin_src elisp
(use-package! oc-biblatex)
#+end_src

*** =oc-bibtex-actions=

**** install

#+begin_src elisp :tangle packages.el
(package! bibtex-actions
  :recipe (:host github
           :repo "bdarcus/bibtex-actions"))
#+end_src

**** configure
#+begin_src elisp
(defvar my/bibs '("~promo/bib/references.bib"))

(use-package! oc-bibtex-actions
  :bind (("C-c b" . org-cite-insert)
         ("M-o" . org-open-at-point)
         :map minibuffer-local-map
         ("M-b" . bibtex-actions-insert-preset))
  :after (embark oc)
  :config
  (setq bibtex-actions-bibliography my/bibs
        org-cite-global-bibliography my/bibs
        org-cite-insert-processor 'oc-bibtex-actions
        org-cite-follow-processor 'oc-bibtex-actions
        org-cite-activate-processor 'oc-bibtex-actions))

;; Use consult-completing-read for enhanced interface.
(advice-add #'completing-read-multiple :override #'consult-completing-read-multiple)
#+end_src
source: https://github.com/bdarcus/bibtex-actions

Am I right to assume that this patched version might help with this?

No. This was just a fork of enhancements that should already be include in org.

You might try exporting and using CSL JSON via Better BibTeX and see if that makes a difference?

Thanks for your quick reply!

Am I right to assume that this patched version might help with this?

No. This was just a fork of enhancements that should already be include in org.

Oh, sorry then. I was getting a bit desperate last night, I guess.

You might try exporting and using CSL JSON via Better BibTeX and see if that makes a difference?

Tried it but still get the same error, unfortunately:

citeproc-bt--to-csl-date: Wrong type argument: stringp, nil

Using this org tree:

#+bibliography: ~/promo/bib/references_bibtex.json
#+cite_export: csl

[cite:@Schmid2016EnglishMorphology]

#+print_bibliography:

And using this minimal json file:

[
	{
		"id": "Schmid2016EnglishMorphology",
		"type": "book",
		"edition": "2",
		"event-place": "Berlin",
		"note": "tex.date-added: 2019-01-17 09:36:26 +0100\ntex.date-modified: 2019-11-05 12:25:07 +0100",
		"publisher": "Erich Schmidt Verlag",
		"publisher-place": "Berlin",
		"title": "English morphology and word-formation - An introduction",
		"author": [
			{
				"family": "Schmid",
				"given": "Hans-Jörg"
			}
		],
		"issued": {
			"date-parts": [
				[
					"2016"
				]
			]
		}
	}
]

I found the error! It was because I had saved forthc. for 'forthcoming' in two entries' year fields in Zotero.

Found it thanks to turning on the debugger during exporting. Oh boy, had I only known earlier that one could use the debugger for this sort of stuff. So glad it works now 😁 Thanks for your help!