{
  "error": {
    "code": "validation_error",
    "message": "Validation failed: merchant_product_id is required.",
    "details": {
      "field_errors": {
        "merchant_product_id": ["This field is required"]
      }
    }
  }
}

{
  "error": {
    "code": "validation_error",
    "message": "Validation failed",
    "details": {
      "field_errors": {
        "line_items": ["At least one line item is required"],
        "customer.email": ["Invalid email format"]
      }
    }
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or missing API key"
  }
}

{
  "error": {
    "code": "not_found",
    "message": "Order not found"
  }
}

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Too many requests. Please try again in 30 seconds."
  }
}