BUG: Package Create: Package with Duplicate Name does not give descriptive error message

Attempt to create a new package with the same name as an already existing package (for example - 'caroles custom package'

You see an error message "An Unknown error occurred"

The message should give more information as is available from rm api

Here is the request and response to/from mod-kb-ebsco

POST https://okapi.frontside.io/eholdings/packages

Body

{"data":{"type":"packages","attributes":{"name":"caroles custom package","contentType":""}}}

Response

{"errors":[{"title":""}],"jsonapi":{"version":"1.0"}}

RM API provides an error message such as below when this happens;

{"errors":[{"code":1009,"subCode":0,"message":"Custom Package with
        the provided name already exists"}]}

This is also visible in the vcr recording for unit test
https://github.com/folio-org/mod-kb-ebsco/blob/master/spec/fixtures/vcr_cassettes/post-custom-package-taken-name.yml