Kha: OpenGL error with official example

https://github.com/Kha-Samples/ComputeShader

GL Error 1280 e:\projects\haxe\kha\kore\backends\graphics4\opengl\sources\kore\computeimpl.cpp 430

GC: GTX 750 Ti, newest nvidia drivers, win 10 up to date, latest Kha

For compiling VS 2017 and make command node ../Kha/make -g opengl