JSX as used with most React projects comes with a very obscure situation
The following doesn't work:

export default () => <div />

You need to import React from 'react' so that the JSX transformation to React.createElement, which appears nowhere in the source, works.

How do we fix this?

• Perhaps transform to Next.createElement which invokes the right adapter (Support for pluggable renderers #20). Downside: extra invocation
• Switch to a JSX compilation that uses plain JavaScript objects and hope that React adopts it (and perhaps other adapters (Support for pluggable renderers #20))