Error Codes
| HTTP | Code | Meaning |
|---|---|---|
| 400 | invalid_request_error | Missing or invalid parameter |
| 401 | authentication_error | Invalid or missing API key |
| 402 | card_error | Card declined |
| 403 | permission_error | Token lacks required scope |
| 404 | not_found | Resource does not exist |
| 429 | rate_limited | Too many requests |
| 500 | api_error | Our problem; retry with backoff |