The following warning message shows up every time bookbrainz is launched:
(node:12871) Warning: a promise was created in a handler at /Users/username/bookbrainz-site/lib/server/helpers/middleware.js:57:4 but was not returned from it, see http://goo.gl/rRqMUw
at Child.fetch (/Users/username/bookbrainz-site/node_modules/bluebird/js/release/method.js:13:13)

There are other places in the code where nothing is returned in promises that should also get fixed