@julian Wouldn't ?? be better?
@freamon As others have said, ChatMessage is non-standard. The Create/Note is not particularly great for private messages, but whatever. Anyway, cc is not a required field of Note nor Create, so any software that would complain has a bug.
Sending a private message without cc causes a 500 error
The logs from this are already cleared on my server, but when I sent a private message (standard Create/Note with a single recipient who also has a Mention in the tag property) from my custom software to my account here, I received a 500 error saying something like "cc is not iterable" (though I don't know the exact phrasing). When I included cc as an empty array, it started working. Not sure whether it was missing on Create or Note, maybe it was both.