It sets request Content-type to application/json but sends no json for GET requests. That makes express to raise an exception. Here's an issue at express repo: strongloop/express#1316
As a work around I replaced application/json with application/x-www-form-urlencoded for GETs:
hash.contentType = (type !== 'GET') ? 'application/json; charset=utf-8' : 'application/x-www-form-urlencoded; charset=utf-8';
This looks like a duplicate of #402.
Closing as duplicate.