Backwards breaking change with `.connect()` return value

[vkarpov15]

Re: #3790 (comment)

[nschloe]

Interestingly, when upgrading to 4.4.1 (from 4.3.x), I noticed that returning the mongoose object doesn't work anymore,

import mongoose from 'mongoose';

export const init = co.wrap(function* _init() {
  yield mongoose.connect(
    config.mongodbUri,
    {
      server: {
        socketOptions: {
          keepAlive: 1,
        },
      },
      replset: {
        socketOptions: {
          keepAlive: 1,
        },
      },
    }
  );

  mongoose.connection.on('error', (err) => {
    process.exit(1);
  });

  return mongoose;
});

always returns undefined. Within this function, it's all fine; mongoose is the fat object it used to be. I'm puzzled as to why this may happen, but perhaps it's related to the attempted fix.

[vkarpov15]

@nschloe can you please open up a separate issue for this? I'm not 100% sure this is related but I'd like to find out if it is...