Can you post the code for "Increase TOC level indentation"? I think you did something wrong there.
And also, that error message shouldn't even be possible. I'm really interested in what allowed (*yaml.Node).DecodeStrict to work on a *kobopatch.Instruction, but decode to a type which isn't either a property or a *kobopatch.PatchableInstruction (which is verified in the unit tests...). Edit: there is one way, I think, which is if you somehow made an instruction null (
https://yaml.org/type/null.html), but I don't see how you'd do that by accident...