Bluebird throws rouge promise warning

[ryanwarsaw]

I was digging through the publish.webmaker.org code to see if I could identify what might be causing some of the downtime issues we've been having today, and I saw this:

6:58 PM
(node:75811) Warning: a promise was created in a handler at domain.js:293:12 but was not returned from it, see http://goo.gl/rRqMUw
    at Function.Promise.cast (/Users/ryanwarsaw/Development/Mozilla/publish.webmaker.org/node_modules/bluebird/js/release/promise.js:196:13)
    at FilesController.update (/Users/ryanwarsaw/Development/Mozilla/publish.webmaker.org/api/classes/base_controller.js:144:28)

Originally Bluebird didn't give me the file that was the origin of the error, so I had to append some verbose code to the Bluebird dependency in order to identify that last line. This might just be a harmless issue, I didn't have enough time to look into it to figure that out.

cc: @gideonthomas

[gideonthomas]

Sorry for getting to this so late. I'm pretty sure this is a harmless error that bluebird is throwing. Hapi passes a callback called reply into our handlers. This callback usually expects a promise chain to be passed in. We create this promise chain in the handler and pass it into the reply callback and since we don't return it (sometimes we do, but it doesn't change anything), bluebird warns us about a promise that hasn't been returned from a function.

On the other hand, the number of connections to the db does not tally with the number of users that are using thimble at a given point of time. I wonder if maybe this might be related to that somehow. I don't really know, but I will take a look and try to dig up what's happening.