CodeSystem/$validate-code & ValueSet/$expand: HTTP 500 "TerminologyError is not a constructor" when a ValueSet depends on an unknown supplement

[jmandel]

Summary

When a value set's compose.include carries a valueset-supplement extension (valueString/valueUri) naming a supplement the server does not have, $expand/$validate-code crash with HTTP 500 and a JavaScript TypeError instead of returning a structured error about the unknown supplement.

Repro (live)

curl -sS -X POST 'https://tx.fhir.org/r4/ValueSet/$expand' \
  -H 'Content-Type: application/fhir+json' -w '\nHTTP %{http_code}\n' -d '{
  "resourceType":"Parameters","parameter":[{"name":"valueSet","resource":{
    "resourceType":"ValueSet","status":"active","compose":{"include":[{
      "system":"http://hl7.org/fhir/administrative-gender",
      "extension":[{"url":"http://hl7.org/fhir/StructureDefinition/valueset-supplement",
                    "valueUri":"http://example.org/no-such-supplement"}]}]}}}]}'

Observed

HTTP 500
{"resourceType":"OperationOutcome","issue":[{"severity":"error","code":"exception","details":{"text":"TerminologyError is not a constructor"},"diagnostics":"TerminologyError is not a constructor"}]}

Likely cause

tx/workers/worker.js:1 does const { TerminologyError } = require('../operation-context'), but operation-context.js does not export TerminologyError (it is exported from tx/library/errors.js). So at worker.js:321 — the checkSupplements "ValueSet depends on supplement '…' that is not known" path — TerminologyError is undefined and new TerminologyError(...) throws is not a constructor, masking the intended clean error. (Controls: with no supplement extension → 200; with the value as valueCanonical instead of valueUri/valueString → 200, because worker.js:319 only reads valueString||valueUri.)

Expected

A structured OperationOutcome reporting the unknown supplement (the intent of the throw), not an uncaught TypeError. (Per http.html, a failure "SHOULD be accompanied by an OperationOutcome"; per operationoutcome.html the issue should state the real reason.) Related: #104 (unknown useSupplement handling).

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Confirmed live against https://tx.fhir.org on 2026-06-06 (software FHIRsmith 0.9.6). Source line refs are from the published main branch.

[grahamegrieve]

fixed