fixes callback validity check
fixes callback validity check

iolevel/peachpie-concept,iolevel/peachpie,peachpiecompiler/peachpie,iolevel/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept,iolevel/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept