http_request issue

[iDevPro]

at Object.moduleWrapper.init (/node_modules/slot/moduleConstructor.js:60:32)
    at/node_modules/slot/app/index.js:193:24
Error: Can't set headers after they are sent. Error: Can't set headers after they are sent.
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11)
    at ServerResponse.header (/node_modules/express/lib/response.js:718:10)
    at ServerResponse.contentType (/node_modules/express/lib/response.js:551:15)
    at ServerResponse.send (/node_modules/express/lib/response.js:138:14)

exports.urls = {
    'about': 'inject'
};

Issue happen when add module init like this: slot.init('moduleName', {items:[...]}, callback); // callback generate this issue