fix bubble up nullable null array item

[benzolium]

Fix case when there is a nullable null value in array item:

type Gizmo {
    id: ID!
    color: String!
}
type Query {
    gizmos: [Gizmo]!
}

{
  "gizmos": [
      { "id": "GIZMO1", "color": "RED" },
      null,
      { "id": "GIZMO2", "color": "GREEN" }
  ]
}