So you're using Gulp and you're thrown a "Potentially unhandled rejection  Error: no writecb" and you have no idea what to do next...
It was my case up to last night when running Gulp for the first time (I usually run Grunt) during the initialization of Wes Bos' "React for Beginners", and the run of a gulp-stylus task.
Initial reaction should be to make sure you're up to date with all components at hand. All modules being all on their latest versions, let's turn to node.
Quick check shows an outdated version, let's get this updated. Here's how to do it.
(sudo) npm cache clean -f (sudo) npm install -g n (sudo) n stable node -v v6.0.0
Try running gulp again. Error should have gone...