At Promise fromNode fromCallback - a promise was created but was not returned from it

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Please answer the questions the best you can:

1. What version of bluebird is the issue happening on?

• 3.7.2

1. What platform and version? (For example Node.js 0.12 or Google Chrome 32)

• Node 12, Heroku worker
• Using babel 7

1. Did this issue happen with earlier version of bluebird? Locally there is no issue at all. I haven’t known about this until I pushed to Heroku.

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I am having this issue on Heroku:

2020-02-19T12:37:49.314100+00:00 app[worker.1]: (node:4) Warning: a promise was created in a handler at internal/process/task_queues.js:79:21 but was not returned from it, see http://goo.gl/rRqMUw
2020-02-19T12:37:49.314102+00:00 app[worker.1]:     at Function.Promise.fromNode.Promise.fromCallback (/app/node_modules/bluebird/js/release/promise.js:206:9)

Since it is pointing to the bluebird node_module directly I assume there might be an issue in the package. (Btw. in the lib at the pointed fromNode.fromCallback there is this weird indentation of a ternary).

[jwalton]

Oh… I bet I know why. I bet the person who raised the issue was creating a Bluebird promise inside the connect handler, which would be run synchronously from inside this block. Sneaky.

[bergus]

I suppose if you really wanted to create a Promise<void>, you could return Promise.resolve() (or return Promise.resolve(undefined)).