second argument for .tap or similar method for rejections

I often use .tap(console.log) for quick debugging. It would be useful for me to have it either work like .then so I could do .tap(null, console.log) as well to log rejections. Or to have a similar method that works like .tap but is analog to .catch as in .tapRejection(console.log).

[benjamingr]

FYI https://github.com/petkaantonov/bluebird/pull/1220

[ajoslin]

I’ve also got a legitimate production usecase: maintaining the lifecycle of a transaction for running sql queries.

Currently I have to do this:

var transaction = sql.transaction()
return action1(transaction)
  .then(() => action2(transaction))
  .then(transaction.commit)
  .catch(function (error) {
    transaction.rollback()
    return Promise.reject(error)
  })

I would prefer to do this:

var transaction = sql.transaction()
return action1(transaction)
  .then(() => action2(transaction))
  .then(transaction.commit)
  .tap(null, transaction.rollback)

Of course, a tapError function would be even better.