trigger a js event when recurlyjs throws a validation error

Problem/Motivation

I want to execute some custom javascript when there is a validation error on the recurlyjs payment form.

There does not seem to be a way to do this currently.

Proposed resolution

trigger a custom js event when there is a recurlyjs validation error. Maybe something like 'recurlyjs-error' ?

I can work on this if the maintainers think its a good addition.