Errors

// The relying-party (Go) path: the SDK unwraps the detail into one typed error.
_, err := client.IssueAuthChallenge(ctx, req)
var se *ydentifi.StatusError
if errors.As(err, &se) {
    switch se.Reason {
    case identity.ErrorReason_LICENSE_USER_CAP_REACHED:
        // at your plan's cap — surface an upgrade prompt
    case identity.ErrorReason_USER_LOCKED:
        // you locked this user; UpdateUserStatus(ACTIVE) unlocks
    case identity.ErrorReason_RATE_LIMIT_EXCEEDED:
        // not before se.AutoExpiresAtUnixMs
    case identity.ErrorReason_INVALID_ARGUMENT:
        // se.Field names the offending input
    }
    log.Printf("ydentifi error trace=%s", se.TraceID)
}
// Or match a sentinel directly:  errors.Is(err, ydentifi.ErrNotFound)

// The device (Swift) path: catch the one typed error enum.
do {
    let ack = try await device.submitChallengeResponse( /* ... */ )
} catch let e as YdentifiDeviceError {
    switch e {
    case .server(let reason, _, let traceID, _, let autoExpiresAt):
        switch reason {
        case .userLocked:        break // locked by the service; no countdown
        case .rateLimitExceeded: break // not before autoExpiresAt
        case .permissionDenied: break // stop — this device isn't allowed
        default:                break
        }
        // include traceID in any support ticket
    case .cryptoFailure:
        // Face ID or Touch ID did not sign. Cancelled: let the user retry.
        // LAError.biometryLockout: unlock with the passcode first.
        // TKError.corruptedData: the key is gone; enrol again.
        break
    default:
        break
    }
}