I don't have any reproduction steps, however one of the featured carts crashed on me earlier today.

The error message that it produced makes me think this is coming from the internals of pico-8 unfortunatly the text is truncated.

I DO NOT have any replication steps. Others have suggested that this error occurs when an error happens with a coroutine.

I did check the code of the cart and the word HEADER didn't appear in it.