fixed null reactElement (#545)
fixed null reactElement (#545)


hammerlab/pileup.js,piotr-gawron/pileup.js,hammerlab/pileup.js,piotr-gawron/pileup.js,piotr-gawron/pileup.js,hammerlab/pileup.js,piotr-gawron/pileup.js,hammerlab/pileup.js