Bug: inactive-code warning omits OperationOutcome expression

[jmandel]

A public tx.fhir.org validation response emits two inactive-code issues for the submitted code. The first issue correctly points at expression: ["code"]; the follow-up inactive warning is about the same submitted code but has no expression, so clients cannot attach that warning back to the offending input element.

Public repro

curl -sS \
  -H 'Accept: application/fhir+json' \
  -H 'Content-Type: application/fhir+json' \
  --data-binary @- \
  'https://tx.fhir.org/r4/CodeSystem/$validate-code' <<'JSON'
{
  "resourceType": "Parameters",
  "parameter": [
    {"name": "url", "valueUri": "http://snomed.info/sct"},
    {"name": "code", "valueCode": "155728006"},
    {"name": "activeOnly", "valueBoolean": true}
  ]
}
JSON

Expected

Both inactive-related issues are about the submitted code parameter, so both should carry expression: ["code"].

Expected issue shape:

{
  "issue": [
    {
      "severity": "error",
      "code": "business-rule",
      "details": {"text": "The concept '155728006' is valid but is not active"},
      "expression": ["code"]
    },
    {
      "severity": "warning",
      "code": "business-rule",
      "details": {"text": "The concept '155728006' has a status of inactive and its use should be reviewed"},
      "expression": ["code"]
    }
  ]
}

Observed

The warning has no expression:

{
  "resourceType": "Parameters",
  "parameter": [
    {"name": "result", "valueBoolean": false},
    {"name": "inactive", "valueBoolean": true},
    {
      "name": "message",
      "valueString": "The concept '155728006' has a status of inactive and its use should be reviewed; The concept '155728006' is valid but is not active"
    },
    {
      "name": "issues",
      "resource": {
        "resourceType": "OperationOutcome",
        "issue": [
          {
            "severity": "error",
            "code": "business-rule",
            "details": {"text": "The concept '155728006' is valid but is not active"},
            "expression": ["code"]
          },
          {
            "severity": "warning",
            "code": "business-rule",
            "details": {"text": "The concept '155728006' has a status of inactive and its use should be reviewed"}
          }
        ]
      }
    }
  ]
}

Why this happens

The inactive state stores a path, and the final inactive warning uses that stored path directly:

// tx/workers/validate.js
if (inactive.value) {
  result.addParamBool('inactive', inactive.value);
  ...
  let m = this.worker.i18n.translate('INACTIVE_CONCEPT_FOUND', this.params.HTTPLanguages, [vstatus.value, tcode]);
  msg(m);
  op.addIssue(new Issue('warning', 'business-rule', inactive.path, 'INACTIVE_CONCEPT_FOUND', m, 'code-comment'));
  // Problem: this depends on inactive.path already being the code element path.
}

But the active-only path stores the parent path, while the immediate error correctly uses addToPath(path, 'code'):

// tx/workers/validate.js
} else if (this.params.activeOnly && await cs.isInactive(loc.context)) {
  result = false;
  if (role !== 'not in') {
    inactive.value = true;
    inactive.path = path;
    // Problem: for a direct code validation, path can be empty, so the later warning has no expression.
    // It should preserve the same path used by the immediate issue below.

    vstatus.value = await cs.getStatus(loc.context);
    let msg = this.worker.i18n.translate('STATUS_CODE_WARNING_CODE', this.params.HTTPLanguages, ['not active', code]);
    messages.push(msg);
    op.addIssue(new Issue('error', 'business-rule', addToPath(path, 'code'), 'STATUS_CODE_WARNING_CODE', msg, 'code-rule'));
    // This issue correctly points at expression ["code"].
  }
}