Stitch & Grunt — File not found

Just started playing with Grunt and would like to use Stitch to combine my modules for the use on the client side. I don’t have much experience with commonJS in general and both libaries are new to me — so please bear with me.

Here's an excerpt from my Grunt file:

var fs     = require('fs');
var stitch = require('stitch');

module.exports = function(grunt) {

  grunt.initConfig({

    … SNIP …

    stitch: {
      dist: {
        src: ['lib'],
        dest: 'dist/<%= pkg.name %>.js'
      }
    }
  });


  grunt.registerMultiTask('stitch', 'Compile common.js modules with stitch', function() {
    var done = this.async();

    var paths = this.file.src.map(function(dir){
      return __dirname + '/' + dir;
    });

    stitch.createPackage({ paths: paths }).compile(function(error, src){
      if (error) {
        return grunt.log.writeln(error);
      }
      file.write(name, src);
      grunt.log.writeln("File '" + name + "' created.");
      done();
    });
  });

};

When running grunt stitch however, I'm getting:

ReferenceError: can't compile  /path/to/file.js
file is not defined

The absolute path is correct, though, and the file does exist.

Any advice would be appreciated.