Sendio.Error (sendio v1.1.0)
Castable module for returning structured errors from the send.io API.
name is the API's error name. Names worth handling by name include
"insufficient_credits" (402: the credit balance does not cover the send,
nothing was sent), "rate_limit_exceeded", "daily_quota_exceeded",
"monthly_quota_exceeded", "subaccount_daily_quota_exceeded" and
"subaccount_monthly_quota_exceeded" (all 429).