{
  "name": "invalid/unknown-type",
  "why": "§4: a wrong type throws",
  "rules": {
    "columns": [
      {
        "key": "v",
        "type": "kr.xxx"
      }
    ]
  },
  "rows": [
    {
      "v": "x"
    }
  ],
  "expect": {
    "throws": "columns[0].type must be one of"
  }
}