Next.js: _document.js - TypeError: Cannot read property 'map' of undefined

@nndung179 is it possible to have a repo with a way for us to reproduce?

node version: 6.5.0
Hi @arunoda

Here is an example:

https://github.com/zeit/next.js/tree/master/examples/with-external-scoped-css

@arunoda I try this example using "next": "2.2.0" works fine.

But using "next": "latest", installs "2.3.0-alpha1", and tends to fail.

Adding this in _document.js works fine. source
```javascript
static getInitialProps ({ renderPage }) {
const {html, head, chunks} = renderPage()
return { html, head , chunks}
}

This problem will occur when nextjs version is 2.3-alpha1,
working good when 2.2.0

I assume this is same as this one: https://github.com/zeit/next.js/issues/2435
Always, try to add the correct stuff for getInitialProps of the custom docs. (Always refer to docs)

Or use this:

import Document from `next/document`

static getInitialProps (ctx) {
   return Document.getInitialProps(ctx)
}