fix double callback for proc.on 'error' and proc.on 'close'
fix double callback for proc.on 'error' and proc.on 'close'

dwrensha/clsi-sharelatex,dwrensha/clsi-sharelatex,EDP-Sciences/clsi-sharelatex,sharelatex/clsi-sharelatex,fancycharts/clsi-sharelatex,sharelatex/clsi-sharelatex,fancycharts/clsi-sharelatex