I am still new to this multiplatform but why is this a type error:

Required: (kotlin.text.Appendable /* = java.lang.Appendable */) -> Unit
Found: (kotlin.text.Appendable) -> Unit

Are you sure that you don’t have typos? Appenable insted of Appen*d*able in your example

Yes. The type error is in the tooltip so its a bit hard to copy paste 😉

I see. strange error, because kotlin.text.Appendable available for JS

Maybe its a spurious error. There are other inconsistencies between an idea build and gradle build 😕

So you still can build your project from console?

If I execute the build task from gradle menu yes. Trying to make a minimal example