title: fsevents.watch error running Gatsby hello-world example
body: <p>I'm trying to do the "Set up your development environment" tutorial on macOS Mojave. Everything is fine until I try to run <code>gatsby develop</code>. When do, I get the errors: "UNHANDLED REJECTION fsevents.watch is not a function" and "TypeError: fsevents.watch is not a function". Does anyone know what to do about that??</p>