PropTypes has moved into it's own package starting with React 15.5+ (https://reactjs.org/blog/2017/04/07/react-v15.5.0.html) so this package is throwing of errors when used with newer versions of React (16, for example).
Change should be pretty straightforward: https://reactjs.org/blog/2017/04/07/react-v15.5.0.html#migrating-from-reactproptypes
Are you accepting PRs?