Don't make data object an empty array on error

[Dkamps18]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Problem/Feature

Historically when the API returned an error the CLI would include a data array in the json response being printed out, however this data array is not returned from the api.
API response

{
	"error": "Not Found",
	"message": "404: Not Found",
	"status": 404
}

CLI Output

{
	"data": [],
	"error": "Not Found",
	"message": "404: Not Found",
	"status": 404
}

Description of Changes:

• Don't initialize an array when data is nil and there is an error message

Checklist

• My code follows the Contribution Guide
• I have self-reviewed the changes being requested
• I have made comments on pieces of code that may be difficult to understand for other editors
• I have updated the documentation (if applicable)