Currently if React is not loaded, ReactDOM shows this:

<img width="664" alt="screen shot 2017-08-08 at 3 36 52 pm" src="https://user-images.githubusercontent.com/810438/29077217-784c7624-7c4f-11e7-88bc-b055407523a9.png">

We should throw a nicer error message in the entry point I think.
throw new Error('Hello');
      }
      expect(() => {
        assertNamespacesMatch(
          <svg {...expectSVG}>
            <BrokenRender />
          </svg>,
        );
      }).toThrow('Hello');
      assertNamespacesMatch(<div {...expectHTML} />);
    });
    it('should unwind namespaces on caught errors', () => {
      function BrokenRender() {
        throw new Error('Hello');
      }
      class ErrorBoundary extends React.Component {