Error Reference
A request can fail twice: at the transport level, or after a 200. A non-2xx status is the first. A 200 with isSuccess: false is the second: the request worked and no data was found. This section covers both, plus the headers that say when and how to retry.
Start with HTTP Status Codes for transport-level failures, Enrichment Errors for why a 200 response can still come back empty, and Rate Limit Headers for tracking and recovering from 429s.