I'm not sure here should exist a `model` or not. Because when `err` is a `ValidationError`, you cannot get readable error messages, but only `__codes`, pass a `model` is helpful. But then it becomes inconsistent with [this](https://github.com/ktmud/jugglingdb/blob/7088e7ad3c4cdbe3c8f0c1606ff4699aef9b0034/test/hooks.test.js#L28-L41).