Charmaker can be found here: https://github.com/coco875/CharMaker. I tried to turn it off and still got the error.
It was in a new save. I used the plugin command OpenCharacterCreator 1.
Well, this charmaker seems to be the same as CCEx, just made right for MZ and still in development.
That said, that seems to be the right plugin command too... So my testing should have given me the same error?
I posted my discord in a previous comment, do you mind sending me a copy of your project so I can try to see it happening? Doesn't need to be it all, or have any media resources outside the rtp and a few character creator pieces, none of the plugins that are not in it when the error happens need to be there either, just one map with one event where it still gives the error. As long as the error still happens in it so I can try to figure it out.
Discord didn't let me message you, so here is the link to the sample project:
https://drive.google.com/file/d/1KeraYeKJS5tzPtOMwtytt7MtjxXk6Q6H/view?usp=shari...