Uncaught Error: Element type is invalid: expected a string

[weichenghsu]

Not sure why this popular package could not be executed correctly with react 16

	"react": "^16.1.0"

	import * as React from 'react';
	import ReactDOM from 'react-dom';
	import Modal from 'react-modal';

	invariant.js:42 Uncaught Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

	Check the render method of `Index`.