{
  "error": {
    "code": "ERROR_CODE",
    "message": "Human-readable description of what went wrong."
  }
}

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "The given data was invalid.",
    "details": {
      "plan_id": ["The plan id field is required."],
      "template_slug": ["The template slug field is required."]
    }
  }
}