Reason-Rc-Null-Pointer-Call

The model receives the prompt (and optional system message). The run uses scorer rubric_json_metrics with the JSON configuration below. Pass/fail and partial credit are determined entirely by that scorer against the model output; no human grading.

Return JSON only with keys answer, evidence, constraints. A function accesses result.data.items[0].name. In some code paths result is null. The function has no null check before this access. What is the root cause of the runtime error?

{
  "metrics": {
    "accuracy": {
      "checks": [
        {
          "contains": [
            "null"
          ]
        },
        {
          "contains": [
            "null check"
          ]
        },
        {
          "contains": [
            "null reference"
          ]
        }
      ]
    },
    "evidence": {
      "checks": [
        {
          "contains": [
            "result is null"
          ]
        },
        {
          "contains": [
            "some paths"
          ]
        },
        {
          "contains": [
            "no guard"
          ]
        }
      ]
    },
    "constraint": {
      "checks": [
        {
          "contains": [
            "missing guard"
          ]
        },
        {
          "contains": [
            "defensive check"
          ]
        },
        {
          "contains": [
            "null-safe"
          ]
        }
      ]
    }
  }
}