fileNames.join is not a function

List files response:
{
  "file_names": ["tests/postgres_tests/test_query.py"]
}
TypeError: fileNames.join is not a function
    at ContextService.<anonymous> (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:53:95)
    at Generator.next (<anonymous>)
    at /home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:8:71
    at new Promise (<anonymous>)
    at __awaiter (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:4:12)
    at ContextService.locationContext (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:52:16)
    at FileContentFetcher.<anonymous> (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/file-content-fetcher.js:23:39)
    at Generator.next (<anonymous>)
    at fulfilled (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/file-content-fetcher.js:5:58)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
Handling exception: TypeError: fileNames.join is not a function
    at ContextService.<anonymous> (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:53:95)
    at Generator.next (<anonymous>)
    at /home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:8:71
    at new Promise (<anonymous>)
    at __awaiter (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:4:12)
    at ContextService.locationContext (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:52:16)
    at FileContentFetcher.<anonymous> (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/file-content-fetcher.js:23:39)
    at Generator.next (<anonymous>)
    at fulfilled (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/file-content-fetcher.js:5:58)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
Stack trace: TypeError: fileNames.join is not a function
    at ContextService.<anonymous> (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:53:95)
    at Generator.next (<anonymous>)
    at /home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:8:71
    at new Promise (<anonymous>)
    at __awaiter (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:4:12)
    at ContextService.locationContext (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/context-service.js:52:16)
    at FileContentFetcher.<anonymous> (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/file-content-fetcher.js:23:39)
    at Generator.next (<anonymous>)
    at fulfilled (/home/runner/work/navie-benchmark/navie-benchmark/submodules/appmap-js/packages/navie/dist/services/file-content-fetcher.js:5:58)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)