There ought to just be a property named something like `defer-validation` that does the right thing. But I'm sure I'm not the first person to suggest it, there's presumably some logistical or technical difficulty.

If I'm making a wish list I'd also like to point a property at a handler function that accepted a `string` and returned a `string | null` (or at least a `nonempty string | empty string`) rather than using an onchange handler, but it is what it is.