[Tarean]

Looks really clean. Does bluebird handle this(https://hackage.haskell.org/package/base-4.9.0.0/docs/Contro...) problem?

    Sometimes you want to catch two different sorts of exception. You could do something like

    f = expr `catch` \ (ex :: ArithException) -> handleArith ex
             `catch` \ (ex :: IOException)    -> handleIO    ex

    However, there are a couple of problems with this approach. The first is that having two exception handlers is
    inefficient. However, the more serious issue is that the second exception handler will catch exceptions in the
    first, e.g.  in the example above, if handleArith throws an IOException then the second exception handler will 
    catch it. 
    Instead, we provide a function catches, which would be used thus:

    f = expr `catches` [Handler (\ex :: ArithException -> handleArith ex),
                        Handler (\ex :: IOException    -> handleIO    ex)]

[idbehold]

Yes.

  .catch(ArithException, IOException, handleError)

Edit: Nevermind, I think what you want to be able to do is provide two different error handlers, but essentially catch them at the same time so that if you throw inside one of them, the second one wouldn't catch it.

[NoInkling]

Not related to the aforementioned Bluebird feature, but I think that's the very reason the promise spec allows you to specify an error callback as the second argument to .then. I guess you can always fallback to an if/switch statement if it's a concern (which is what you'd do with await and try/catch).

[tkxxx7]

this library does: https://github.com/bigeasy/cadence