Errors

Exceptions mirror the JavaScript hierarchy (TypeSafeError → TypeSafeException, and so on).

Type	When
TypeSafeException	Validation / configuration
ApiException	Non-2xx after retries
BadRequestException	400
AuthenticationException	401
PermissionDeniedException	403
NotFoundException	404
UnprocessableEntityException	422
RateLimitException	429
InternalServerException	5xx
ApiConnectionException	Transport failure
ApiTimeoutException	Attempt timed out
ApiUserAbortException	Cancelled CancellationToken

Catch more specific types first when you need distinct handling for auth vs rate limits vs timeouts.