Unfortunately, I don’t. I’m somewhat new to Ember Data myself. I was hoping somebody more knowledgable and experienced would weigh in with an opinion. From what I saw in this - http://reefpoints.dockyard.com/2014/04/29/the-problem-with-server-rendered-errors.html - handling server side errors can be a thorny problem to generalize.
Update: I would read Ember Data, ActiveModelAdapter, and Validations for further discussion on the topic.