Warning: a promise was created in a handler but was not returned from it

[shun-tak]

I have got a bluebird warning.

Warning: a promise was created in a handler but was not returned from it is occuring at lib/client.jsL170

Warning: a promise was created in a handler but was not returned from it
https://github.com/petkaantonov/bluebird/blob/master/docs/docs/warning-explanations.md

I added a line to client.js:

this.hosts = hosts;
this.connectToHosts();
this.flushBuffer();
+ return Promise.resolve();

and the warning is disappeared though return Promise.resolve() doesn't look good.

Stack traces are like:

Warning: a promise was created in a handler at anonymous> (/home/share/shun_tak/project/node_modules/memcache-plus/lib/client.js:170:14 but was not returned from it, see http://goo.gl/rRqMUw
    at new Promise (/home/share/shun_tak/project/node_modules/bluebird/js/release/promise.js:77:14)
    at Object.exports.defer (/home/share/shun_tak/project/node_modules/memcache-plus/lib/misc.js:15:19)
    at Connection.get (/home/share/shun_tak/project/node_modules/memcache-plus/lib/connection.js:713:25)
    at Client.flushBuffer (/home/share/shun_tak/project/node_modules/memcache-plus/lib/client.js:219:48)
    at Client.<anonymous> (/home/share/shun_tak/project/node_modules/memcache-plus/lib/client.js:170:14)
From previous event:
    at Client.getHostList (/home/share/shun_tak/project/node_modules/memcache-plus/lib/client.js:167:26)
    at Client.connect (/home/share/shun_tak/project/node_modules/memcache-plus/lib/client.js:79:14)
    at new Client (/home/share/shun_tak/project/node_modules/memcache-plus/lib/client.js:61:10)
    at Object.<anonymous> (/home/share/shun_tak/project/handlers/sample.js:9:19)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Module.require (module.js:353:17)
    at require (internal/module.js:12:17)
    at AwsInvokeLocal.invokeLocalNodeJs (/usr/lib/node_modules/serverless/lib/plugins/aws/invokeLocal/index.js:79:16)
    at AwsInvokeLocal.invokeLocal (/usr/lib/node_modules/serverless/lib/plugins/aws/invokeLocal/index.js:61:19)
    at processImmediate [as _immediateCallback] (timers.js:383:17)

I will appreciate your help with this situation.