(Update for SPFx v1.7 - 2018-11-09)
This post is still valid for SPFx v1.7
When installing a reference to Office UI Fabric React make sure to run
npm i office-ui-fabric-react@lts --save
and not
npm i office-ui-fabric-react@latest --save
Lts is the latest stable version, which currently is v5.122.1 and in this case compatible with React 15 which is what SPFx uses. The latest version is 6.57.0 which require React 16, and won’t build with SPFx.
Stable photo by Ryan Yeaman at Unsplash