can't get the contact data

[mydearxym]

query contacts in graphql-playground get error

{
  user(id: 1) {
    name
    contacts {
      type
    }
  }
}

{
  "errors": [
    {
      "path": [
        "user",
        "contacts",
        0,
        "type"
      ],
      "message": "Cannot return null for non-nullable field",
      "locations": []
    }
  ],
  "data": {
    "user": {
      "name": "Test",
      "contacts": [
        null
      ]
    }
  }
}

but query post seems right

{
  user(id: 1) {
    name
    posts {
      title
    }
  }
}

{
  "data": {
    "user": {
      "posts": [
        {
          "title": "Test Post"
        }
      ],
      "name": "Test"
    }
  }
}

PS: already insert the seed data

[mydearxym]

figured.