Node.js test script not executing with Appium for iOS

Question

I've successfully integrated Appium desktop app and works fine by following this tutorial: http://latestsoftwaretestingnews.com/mobiletesting/appium-ios-testing-with-node-js-step-by-step-guide/

main.js

describe ('Simple cases', function (){
      before (function (){
        this.timeout(50000);
        return client.init();
      });
      describe('test-app-addition', function (){
        it('add-3-3', function(){
          return client.element('~IntegerA')
          .setValue ('3')
          .elementByAccessibilityId ('~IntegerB')
          .setValue('3')
          .click('~ComputeSumButton')
          .element('~Answer')
          .getText()
          .then(function (text){
            expect(text).to.equal('6');
          });
        });
      });
      after(function(){
        return client.end();
      });
    });

but on executing $npm run native command getting an error. Refer screenshot

Appreciate your help and suggestions!

Thanks