doesn't work with the async stuff in line 23

app.js

var http = require('http'),
    util = require('util'),
    formidable = require('formidable'),
    server;

global.TEST_PORT = 13532;

server = http.createServer(function(req, res) {
    if (req.url == '/') {
      res.writeHead(200, {'content-type': 'text/html'});
      res.end(
        '<form action="/post" method="post">'+
        '<input type="text" name="title"><br>'+
        '<input type="text" name="data[foo][]"><br>'+
        '<input type="submit" value="Submit">'+
        '</form>'
      );
    } else if (req.url == '/post') {
      console.log('got post request');
      var form = new formidable.IncomingForm(),
          fields = [];
      req.pause();
      process.nextTick(function(){
        req.resume();
        form
          .on('error', function(err) {
            res.writeHead(200, {'content-type': 'text/plain'});
            res.end('error:\n\n'+util.inspect(err));
          })
          .on('field', function(field, value) {
            fields.push([field, value]);
          })
          .on('end', function() {
            console.log('on end -> post done');
            res.writeHead(200, {'content-type': 'text/plain'});
            res.end('received fields:\n\n '+util.inspect(fields));
          });
        form.parse(req);
      });
    } else {
      res.writeHead(404, {'content-type': 'text/plain'});
      res.end('404');
    }
});
server.listen(TEST_PORT);

util.puts('listening on http://localhost:'+TEST_PORT+'/');