Using rollup.js for web builds instead of webpack has unexpected results.

[MichaelRando]

I observed that rollup tree shaking did not work using rollup.js and the following import:
import Menu from 'semantic-ui-react'
import Header from 'semantic-ui-react'

It also seems that rollup is breaking a subset of the mass imports where the 'react.createElement(ElementType' first parameter string was being substituted to '_default'; (for example Radio.js) which must be a consequence of pattern
index.js:
import _default from './Radio';
export { _default as default };

I've worked around the issue by using:
import Menu from '../../node_modules/semantic-ui-react/dist/es/collections/Menu/Menu'
import Header from '../../node_modules/semantic-ui-react/dist/es/elements/Header/Header'

instead.

It's certainly possible that this is a issue with rollup, rather than es target. But I'm leaving the bug here to encourage investigation on why the es target does not work; since my workaround is sufficient to unblock developers, but it's still an issue that others will likely run into.

[layershifter]

import Menu from 'semantic-ui-react'
import Header from 'semantic-ui-react'

It' a typo? It must be:

import { Menu, Header } from 'semantic-ui-react'

[MichaelRando]

import { Header, Menu } from 'semantic-ui-react'
confirmed same broken results. The typo version was a failed workaround in my edit history, this must've been the original docs cut-and-paste.

[layershifter]

Linking with #1237.