Correct Node Custom Error Handling Pattern for use with Promises?

Gist Here

New to Node, and I'm curious as to the best way to create and handle custom errors when using Promises. In the example I put my application errors in a module which I use to throw and catch errors. This example is a little old, as I updated it to return a Promise rejection with the error in it, but the example still stays.

Am I doing it wrong by wrapping Errors in a module?