bluebird warning

[Michael McLaughlin]

the following warning is encountered when authing for this project:
https://github.com/characterastronomy/backend
front end is here: https://github.com/characterastronomy/web-ui

but basically, when you unlink, and just call this function the following warning occurs:

(node:67680) Warning: a promise was created in a handler at /characterastronomy/react-auth-server/node_modules/express/lib/router/index.js:317:13 but was not returned from it, see http://goo.gl/rRqMUw
    at Function.Promise.attempt.Promise.try (/characterastronomy/react-auth-server/node_modules/bluebird/js/release/method.js:29:9)

function setProviders(id, providers) {
  return connection
    .from('users')
    .where('id', id)
    .update('providers', providers)
    .returning('*')
    .then(([user]) => user)
}