emberjs/ember.js — pull request #3743 by rjackson (2013-11-15 16:07:14+00:00)
Title: [BUGFIX beta] Register a default RSVP.onerror handler.

This will significantly improve the users experience when debugging errors
thrown in promises as they will now be logged to the console in development.

This could easily be made into a feature, but in my opinion the sad state of
promise errors is a significant bug (hence the `[BUGFIX beta]` tag).