I think it would make sense for `.validate()` to populate defaults for `null` values. ``` js var Doc = thinky.createModel('docs', { id: String, price: { _type: Number, default: 0 } }, { enforce_type: 'strict' }); ``` Works as expected when `doc.price` is `undefined`: ``` js var doc = new Doc({ id: 'UUID' }); doc.validate(); // doc.price === 0 ``` Doesn't work when `doc.price` is `null`: ``` js var doc = new Doc({ id: 'UUID', price: null }); doc.validate(); // throws "Value for [price] must be a number." ```