Something is wrong when we expect high quality libraries for free. The authors are highly skilled individuals with mortgages to pay and children to feed. Not sure what the answer is. If coupling Observable with d3 is such an answer, then more power to them. Related, I've stumbled upon this blurb from Codemirror6. Perhaps another answer.
If you are using CodeMirror commercially, there is a social expectation that you help fund its maintenance.
If you are using CodeMirror commercially, there is a social expectation that you help fund its maintenance.
https://codemirror.net/6