I remember getting similar messages back in 2015 when I used datascript.

I think it might be schema conflicting with the object you are passing in? That's a very vague guess.

The error fixed itself, by that I mean I don't have the slightest idea what changed and how it got fixed, 😛

I know the feeling all too well 😞

if/when you remember, feel free to open up an issue or PR here: https://github.com/Lokeh/datascript-notes

i’m collecting these oft-forgotten tidbits of info

One issue I faced is DS does not validate the schema itself. I mistyped :db/valueType as :db/value but it did not complain.

Schema's are open, meaning you can extend them with other metadata about your attributes (both in Datomic & in DataScript).