AppThreadPage thread query error

appThreadPage.graphql

query AppThreadPage {
  appThreadPage(uuid: "5a266409-d835-4e27-956a-569e63f553b6") {
    users { name }
    
    related_to_block { uuid }
    
    threads {
      single_block_exchange { uuid }
    
      thread { uuid }
    }
  }
}

response.json

{
  "errors": [
    {
      "message": "Can't resolve value (/appThreadPage/threads[0]/thread) : type mismatch error, expected type LIST",
      "path": [
        "appThreadPage",
        "threads",
        0,
        "thread"
      ],
      "extensions": {
        "classification": "DataFetchingException"
      }
    }
  ],
  "data": {
    "appThreadPage": {
      "users": [
        {
          "name": "Mr. Kovacs"
        },
        {
          "name": "Fotios Siskellis"
        }
      ],
      "related_to_block": null,
      "threads": [
        {
          "single_block_exchange": [],
          "thread": null
        }
      ]
    }
  }
}