vm: fix GC safety issue in non-optimizing compiler
vm: fix GC safety issue in non-optimizing compiler

tgunr/factor,sarvex/factor-lang,bjourne/factor,sarvex/factor-lang,bjourne/factor,bpollack/factor,AlexIljin/factor,AlexIljin/factor,sarvex/factor-lang,tgunr/factor,nicolas-p/factor,bpollack/factor,mrjbq7/factor,dch/factor,AlexIljin/factor,dch/factor,dch/factor,dch/factor,AlexIljin/factor,nicolas-p/factor,sarvex/factor-lang,slavapestov/factor,factor/factor,AlexIljin/factor,factor/factor,nicolas-p/factor,tgunr/factor,nicolas-p/factor,slavapestov/factor,mrjbq7/factor,slavapestov/factor,slavapestov/factor,dch/factor,bpollack/factor,factor/factor,nicolas-p/factor,bjourne/factor,sarvex/factor-lang,bpollack/factor,bpollack/factor,factor/factor,bpollack/factor,slavapestov/factor,bjourne/factor,tgunr/factor,slavapestov/factor,nicolas-p/factor,tgunr/factor,AlexIljin/factor,sarvex/factor-lang,tgunr/factor,factor/factor,factor/factor,mrjbq7/factor,bjourne/factor,mrjbq7/factor,sarvex/factor-lang,slavapestov/factor,dch/factor,bpollack/factor,bjourne/factor,AlexIljin/factor,mrjbq7/factor,nicolas-p/factor,bjourne/factor,mrjbq7/factor