NodeJS client error code is http statuscode, not commercetools error code

I believe that since the HTTP statuscode is already available on both error.status and response.statusCode, the field error.code should contain the commercetools error code string, as documented on https://docs.commercetools.com/api/errors.

Read the commercetools API errors documentation first, then inspect the Node.js client error-handling path where error.status, response.statusCode, and error.code are populated. Done means error.code contains the documented commercetools error code while the HTTP status remains available through the existing status fields.

Written by the indexing model from the issue text.