Allow null as newValue in InsertElement?

[jonaskello]

It seems InsertElement does not allow inserting the value null into an array. Shouldn't this be allowed?

So instead of this:

export interface InsertElement {
  // ...
  readonly newValue: GraphQLCache.EntityFieldValue;
}

We would have this:

export interface InsertElement {
  // ...
  readonly newValue: GraphQLCache.EntityFieldValue | null;
}

[jonaskello]

This is related to gql-cache #26. If EntityFieldValue is updated to include null then this fix is not needed.

[jonaskello]

Actually it seems like this was already fixed. EntityFieldValue includes null in gql-cache 0.9.1, see #25.