Bluebird forgotten return warning is missing

I expect Bluebird forgotten return warning to appear but it doesn't work for some reason.

A demo:

const Bluebird = require('bluebird');

Bluebird.config({
    warnings: true
})

Bluebird.resolve(1)
.then(() => {
    Bluebird.resolve(2); // should warn about forgotten return
})
.then(two => console.log(two));

How can it be fixed to output a warning?

I suspect I already encountered this problem before but I don't remember what was the solution.

from Bluebird forgotten return warning is missing