Can't get GraphQL working for tree and singleton

[letima]

I would like to use GraphQL to query elements in the playground (By the way: is there any documentation how to authorize with GraphQL). If I use an API key in the playground, I only get an “Internal Server Error” with Singleton and Tree. Collections work fine.
If I omit the API key then I get empty objects back.

My JSON:

{
  SeitenModel {
    _id
    _created
    _modified
    Menuetitle
    Seitentitel
    Permalink
    Keywords
  }
}

I get:

{
  "errors": [
    {
      "message": "Internal server error",
      "extensions": {
        "category": "internal"
      },
      "locations": [
        {
          "line": 6,
          "column": 2
        }
      ],
      "path": [
        "SeitenModel",
        0,
        "Menuetitle"
      ]
    },
    {
      "message": "Internal server error",
      "extensions": {
        "category": "internal"
      },
      "locations": [
        {
          "line": 6,
          "column": 2
        }
      ],
      "path": [
        "SeitenModel",
        1,
        "Menuetitle"
      ]
    },
    {
      "message": "Internal server error",
      "extensions": {
        "category": "internal"
      },
      "locations": [
        {
          "line": 6,
          "column": 2
        }
      ],
      "path": [
        "SeitenModel",
        2,
        "Menuetitle"
      ]
    },
    {
      "message": "Internal server error",
      "extensions": {
        "category": "internal"
      },
      "locations": [
        {
          "line": 6,
          "column": 2
        }
      ],
      "path": [
        "SeitenModel",
        3,
        "Menuetitle"
      ]
    },
    {
      "message": "Internal server error",
      "extensions": {
        "category": "internal"
      },
      "locations": [
        {
          "line": 6,
          "column": 2
        }
      ],
      "path": [
        "SeitenModel",
        4,
        "Menuetitle"
      ]
    }
  ],
  "data": {
    "SeitenModel": [
      null,
      null,
      null,
      null,
      null
    ]
  }
}

[letima]

I’ve now tried it outside of the playground (a query via PHP and curl). Also here I get an internal server error.
As I said, I get everything clean via the REST API, with GraphQL only collections work properly. Unfortunately, I can’t find any errors either - neither in my script (there’s not much there) nor in Cockpit.
The error message (extension and location) doesn’t really help me.

EDIT: I got it worked on Singleton also. For another tree I get an empty object nevertheless I added items in the backend.

[faridbouchdak]

I can’t reproduce your errors.
Tree-collection:

GraphQl:

Singleton:

Both are with API-key:

Make sure you give the role that contains the API-key the right permissions and that the items are published.