MapLibreParticleLab/metrics/integration/expression-tests/match/label-object/test.json

{
  "expression": ["match", "x", {}, "thing one", "thing two"],
  "expected": {
    "compiled": {
      "result": "error",
      "errors": [
        {"key": "[2]", "error": "Branch labels must be numbers or strings."}
      ]
    }
  }
}