Adjust integration test to work with correct error coming from error.message
Adjust integration test to work with correct error coming from error.message

metaraine/sendgrid-nodejs,sendgrid/sendgrid-nodejs,pandeysoni/sendgrid-nodejs,vermaslal/sendgrid-nodejs,sendgrid/sendgrid-nodejs,mauricionr/sendgrid-nodejs,sendgrid/sendgrid-nodejs,XEuRoMAN/sendgrid-nodejs