Discussion on: Promise Chains are Kinda Awesome

Excellent question!

If you want to use Promise as your container, as we've done in the examples, you can forward the exceptions from the fetchers in a local catch block:

const rethrow = message => err => { 
  throw new Error(`${message} ${error}`)
}

const fetchGuests = () => 
  fetch('/friends')
    .catch(rethrow('Could not fetch guests');

etc. season to taste, then handle them in the top level flow's catch block.

If you want to go buck wild though, you could toss in a few natural transformations. That however, will have to wait for another post :D