List observations for an experiment

{
  "data": [
    {
      "id": 0,
      "experimentId": "7cb83992-f615-4081-9f22-54e0b618e006",
      "idx": 0,
      "expected": "string",
      "variables": {
        "property1": null,
        "property2": null
      },
      "split": "string",
      "createdAt": "string"
    }
  ]
}

{
  "error": "string"
}