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

1. What version of bluebird is the issue happening on? - 3.4.7
2. What platform and version? – Chrome, Firefox, Safari (require('bluebird') + browserify)
3. Did this issue happen with earlier version of bluebird? - no, 2.9*

Should not .done() to suppress the warning?

// some button.js
function onClick() {
    this.loadOptions()
        .then((options) => {
            // some external event interface
            this.trigger('loaded', options); // sync
        })
        .done();
}

// some external button listener like table.js
button.on('loaded', (e, options) => {
    this.loadSomeData(options)
        .then((data) => {
            this.updateSelf(data); // sync
        })
            .done();
});

We have warning bacause promise from loadSomeData() created in a handler of promise from loadOptions()

Also I think this warning works strange, two examples:

function test1() {
    Bluebird
        .resolve()
        .done(() => {
            Bluebird.resolve().done();
        });
}

no warning above

function test2() {
    Bluebird
        .resolve()
        .then(() => {
            Bluebird.resolve().done();
        })
        .done();
}

warning happened

Guess the examples are equal, but warning happening

I think that in both cases, the warning shouldn’t be happen, because it is not possible to return promise in any case.

PS: all the examples are full synthetic but reflecting real cases

PPS: http://bluebirdjs.com/docs/api/promise.config.html#promise.config it says that all the options are false by default, but I get the warnings while not explicitly set {warnings: false}

[akhoury]

bluebird was getting loaded by other third party libraries, so this didn’t work for me, not sure why, maybe the other libs are overriding this config at some point.

require('bluebird').config({
  warnings: {
    wForgottenReturn: false
  }
});

However, this did

process.env.BLUEBIRD_W_FORGOTTEN_RETURN = 0;

source: http://bluebirdjs.com/docs/api/promise.config.html

[adamreisnz]

If you know what you’re doing and don’t want to silence all warnings, you can create runaway promises without causing this warning by returning null

I did pick up on that, but that’s hardly a solution either as it requires me to refactor a lot of my code, and doesn’t solve the issue with warnings originating from 3rd party libraries.

In the end I found this to disable these pesky warnings:

Promise.config({
    // Enables all warnings except forgotten return statements.
    warnings: {
        wForgottenReturn: false
    }
});