Why does stryker throw "foo()" is not a function

[SDolnutu]

Question

Upon starting stryker with just "stryker run" the following error is being presented:

ERROR Stryker[39m Unexpected error occurred while running Stryker { Error: Could not resolve [token "options"] -> [function markOptions]. Cause: Object.entries(...).flatMap is not a function

Stryker environment

This is how my config looks like:

"_comment": "This config was generated using 'stryker init'. Please see the guide for more information: https://stryker-mutator.io/docs/stryker-js/guides/angular",
  "mutate": [
    "**/*.ts",
    "!**/*.spec.ts",
    "!**/*test.ts"
  ],
  "testRunner": "jest",
  "jest": {
    "projectType": "custom",
    "configFile": "jest.config.js",
    "config": {
      "testEnvironment": "jest-environment-jsdom-sixteen"
    },
    "enableFindRelatedTests": true
  },
  "reporters": [
    "progress",
    "clear-text",
    "html"
  ],
  "concurrency": 4,
  "concurrency_comment": "Recommended to use about half of your available cores when running stryker with angular",
  "coverageAnalysis": "perTest",
  "allowConsoleColors": true,
  "checkers": [],
  "maxTestRunnerReuse": 0,
  "commandRunner": {
    "command": "npm test"
  },
  "clearTextReporter": {
    "allowColor": true,
    "logTests": true,
    "maxTestsToLog": 3
  },
  "dashboard": {
    "baseUrl": "https://dashboard.stryker-mutator.io/api/reports",
    "reportType": "full"
  },
  "eventReporter": {
    "baseDir": "reports/mutation/events"
  },
  "ignorePatterns": [],
  "fileLogLevel": "off",
  "inPlace": false,
  "logLevel": "trace",
  "maxConcurrentTestRunners": 9007199254740991,
  "mutator": {
    "plugins": null,
    "excludedMutations": []
  },
  "plugins": [
    "@stryker-mutator/*"
  ],
  "appendPlugins": [],
  "jsonReporter": {
    "fileName": "reports/mutation/mutation.json"
  },
  "disableTypeChecks": "{test,src,lib}/**/*.{js,ts,jsx,tsx,html,vue}",
  "symlinkNodeModules": true,
  "tempDirName": ".stryker-tmp",
  "cleanTempDir": true,
  "testRunnerNodeArgs": [],
  "thresholds": {
    "high": 80,
    "low": 60,
    "break": null
  },
  "timeoutFactor": 1.5,
  "timeoutMS": 5000,
  "dryRunTimeoutMinutes": 5,
  "tsconfigFile": "tsconfig.json",
  "warnings": true,
  "configFile": "/var/lib/jenkins/workspace/mutation-testing/stryker.conf.js"
}

"@stryker-mutator/core": "^5.1.1",
"@stryker-mutator/jest-runner": "^5.1.1",

+-- [email protected]

Additional context

NPM version on Jenkins machine, where im trying to run the mutation tests, is 6.14.4

[stale[bot]]

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