Re: the json error, I found it works if you use the MSYS Makefiles generator when using msys. So:
cmake --fresh -B build -G "MSYS Makefiles"
Then it works. The problem is the two types of paths on msys/mingw/windows (C:/... vs /c/...). Using MSYS Makefiles “just works”. I’m updating the sdk README to include this.
BTW I played around with trying to convert the path from within cmake, but couldn’t get it to work without lots and lots of checks and running external programs. Detecting which type of path the currently running shell will want is not simple… I suppose that’s why there’s a cmake generator to handle all these issues.