How to catch database operation errors

@jreklund is right,
i must add that API CONTROLLER has to handle the error processing, also please read on and implement correct REST API responses and http response codes, and JQUERY knows how to handle them

what i would do is to check the result of the DB queries in the CONTROLLER and then return corresponding http headers and the payload (null, false, or nothting {}). then JQUERY can detect and handle the appropriate action.