This is wrong:

{
  "name": "chunks",
  "type": "object[]",
  "fields": [
    {
      "name": "text",
      "type": "string"
    },
    {
      "name": "vector",
      "type": "float[]",
      "num_dim": 5
    }
  ]
}

You can't nest fields this way in the schema. You have to use dot notation to refer to nested fields. E.g.

chunks.vector