code: function(step, next) {
        var oldNext;
        if (!step.options.errorHandler) {
          next();
          return;
        }
        oldNext = step.next;
        step.next = function() {
          try {
            return oldNext.apply(null, arguments);
          } catch (error) {
            return step.options.errorHandler(step, error);
          }
        };
        return next();
      }
docs: /*{"name":"ctrl.builders.errorHandler", "priority":5}
  This builder adds error handling to the step object.
  If a function is passed in as `errorHandler` to the options
  parameter that function will be called in the event of an error.