initialize state to null if not when not set

[mattfysh]

Fixes #1249

Checklist:

• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests
• If this was a change that affects the external API used in GitHunt-React, update GitHunt-React and post a link to the PR in the discussion.

[mattfysh]

This fixes an issue with react-emotion due to an explicit check in their library for null:

https://github.com/emotion-js/emotion/blob/master/packages/react-emotion/src/index.js#L82

The react-apollo SSR walk needs to be updated to match React behaviour, i.e. isNull(this.state)

[mattfysh]

@jbaxleyiii - this is a rework of #1300 applied to latest master, however tests in an unrelated area are failing. Does this mean they are also failing in master? I can't see any changes I've made that could affect the unit tests that are breaking. Thanks! 👍

[jbaxleyiii]

@mattfysh yep not you! That's a flaky test I need to rewrite haha