browserifying node-minecraft-protocol yggdrasil auth -> superagent -> mime, fs.readFileSync mime type reading error

gistfile1.txt

try.js:

var mime = require('mime');

browserify try.js > b.js
<script src="b.js"></script>

 Uncaught TypeError: undefined is not a function
 b.js:2621 module.exports.load
 b.js:2662 (anonymous function)
 b.js:2670 20.fs
 b.js:1 s
 b.js:1 (anonymous function)
 b.js:1094 9../utils
 b.js:1 s
 b.js:1 (anonymous function)
 b.js:209 (anonymous function)
 b.js:1031 4../agent
 b.js:1 s
 b.js:1 (anonymous function)
 b.js:2940 (anonymous function)
 b.js:2954 23.mime
 b.js:1 s
 b.js:1 e
 b.js:1 (anonymous function)
 
   /**
   * Load an Apache2-style ".types" file
   *
   * This may be called multiple times (it's expected).  Where files declare
   * overlapping types/extensions, the last file wins.
   *
   * @param file (String) path of file to load.
   */
  load: function(file) {
    // Read file and split into lines
    var map = {},
        content = fs.readFileSync(file, 'ascii'),  // <-- *** crashes here, no fs.readFileSync
        
file = "/node_modules/superagent/node_modules/mime/types/mime.types"
fs.readFileSync unavailable in browserify
except for constant literal paths with https://github.com/substack/brfs, but this path is not "constant"
 can it be made so?
called from:


// Load our local copy of
// http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types
mime.load(path.join(__dirname, 'types/mime.types'));

// Overlay enhancements submitted by the node.js community
mime.load(path.join(__dirname, 'types/node.types'));

mime 1.3.4


superagent 0.10.0 uses mime 1.2.5
lib/node/part.js
var utils = require('./utils')
  , Stream = require('stream').Stream
  , mime = require('mime')

browserifying superagent:

var superagent = require('superagent');

global.superagent = superagent;

console.log('about to post');
superagent.post('http://cors.maxogden.com/')
  .type('json')
  .send({k: "v"})
  .end(function (resp) {
    console.log(resp);
  });
  
same crash

superagent has browser support in lib/client.js (uses XMLHttpRequest), why isn't it being used?
is it supposed to be? superagent/package.json doesn't have a "browser" field

[not that it would work in browserified node-minecraft-protocol anyway - or more specifically,
the yggdrasil auth https://github.com/PrismarineJS/prismarine-yggdrasil - as it contacts
https://authserver.mojang.com, which is not CORS-enabled (and probably won't be).]


see also:
superagent vs https://github.com/request/request? 
http://nodejs.org/api/http.html + https://www.npmjs.com/package/http-browserify