Ember get-with-default

get-with-default.js

import Ember from "ember";

export default Ember.Helper.helper(function([obj, path, defaultValue]){
  if (Ember.isEmpty(path)) {
    // or throw an error
    return;
  }

  return obj ? Ember.get(obj, path) || defaultValue : defaultValue;
});

Your return could be simplified:
return Ember.getWithDefault(obj, path, defaultValue);