luvit: uv: Stream: guard against writing to closed stream
luvit: uv: Stream: guard against writing to closed stream

writing to a closed stream will cause an error, avoid doing that.

boundary/luvit,boundary/luvit,GabrielNicolasAvellaneda/luvit-upstream,luvit/luvit,AndrewTsao/luvit,DBarney/luvit,connectFree/lev,connectFree/lev,AndrewTsao/luvit,AndrewTsao/luvit,boundary/luvit,GabrielNicolasAvellaneda/luvit-upstream,sousoux/luvit,sousoux/luvit,sousoux/luvit,DBarney/luvit,kaustavha/luvit,rjeli/luvit,boundary/luvit,sousoux/luvit,zhaozg/luvit,boundary/luvit,boundary/luvit,kaustavha/luvit,bsn069/luvit,zhaozg/luvit,bsn069/luvit,sousoux/luvit,GabrielNicolasAvellaneda/luvit-upstream,sousoux/luvit,luvit/luvit,rjeli/luvit,rjeli/luvit,kaustavha/luvit,DBarney/luvit,DBarney/luvit,rjeli/luvit,GabrielNicolasAvellaneda/luvit-upstream,bsn069/luvit