@defer + errors / nullability

Hey, thanks for the great talk about "experiements in GraphQL," so many good ideas there!

I'm exploring `@defer` and I have a couple clarifying questions about error handling.

Let's say you have a non-null field on an object which returns null (bad). The spec says the error should "propagate," making the parent object null:

> However, if the type of that field is of a Non-Null type, since the field cannot be null the error is propagated to be dealt with by the parent field.

([Error Handling](http://facebook.github.io/graphql/#sec-Error-handling))

So,
1. In that case, should we cancel all deferred fields whose parents were cancelled?
2. If a non-null field was deferred, but returns null, should we patch the parent object to be null? Or simply _not issue_ a patch for that illegally-null field?