Service worker registration failing in build

[Kurohyou]

My extension is working perfectly when I'm building with dev (npm run dev). However, when I use npm run build and try to load the unpacked extension in chrome, chrome gives Service worker registration failed. Status code: 3 and highlights the service worker specification in the manifest as the issue:

 "background": {
    "service_worker": "service-worker-loader.js",
    "type": "module"
  }

Anyone have some ideas of what I can check to see what exactly is going wrong here?