'use strict';

define('<%= main_module_name %>',
  [
    // Add your dependencies here
    'jquery',
    'jquery-ujs'
  ],

  function($){

    function initialize(){
      // Add your initialization code here
    }

    return initialize;

  }
);

'use strict';

define('<%= main_module_name %>',
  [
    // Add your dependencies here
    'jquery',
    'jquery-ujs'
  ],

  function($){

      // Add your initialization code here

  }
);

Remove nesting for init module