unsupported type for static module: VariableDeclarator

[lostinplace]

when running browserify js/pre-bro.app.js using brfs, I receive the following error:

Error: unsupported type for static module: VariableDeclarator
at expression:

  fs
 while parsing file: /Users/me/dev/git/studio-module-media/js/pre-bro.app.js
  at traverse (/Users/me/dev/git/studio-module-media/node_modules/brfs/node_modules/static-module/index.js:285:25)

I have determined that the lines from the source file that trigger this error are the following:

...
// Generated by CoffeeScript 1.8.0
(function() {
  var $, Definition, Marionette, QuickPublishView, Studio, Template, fs, _;

  $ = require('jquery');

  _ = require('underscore');

  fs = require('fs');
....

I'm having trouble figuring out what's going on