{
  "expression": ["length", ["get", "x"]],
  "inputs": [
    [{}, {"properties": {"x": "a string"}}],
    [{}, {"properties": {"x": []}}],
    [{}, {"properties": {"x": 0}}]
  ],
  "expected": {
    "compiled": {
      "result": "success",
      "isFeatureConstant": false,
      "isZoomConstant": true,
      "type": "number"
    },
    "outputs": [
      8,
      0,
      {
        "error": "Expected value to be of type string or array, but found number instead."
      }
    ],
    "serialized": ["length", ["get", "x"]]
  }
}