7.1.0 breaks docker - peer dependency module 'helmet'
I have spent about 10 hours trying to figure this out and this is what I know for sure:

- 7.0.2 worked both locally as well as when built and ran through docker
- 7.1.0 works locally, not when built through docker unless using webpack to include the source code in a singular file

By broken I mean that my app cannot find this module under `node_modules` when installed through docker, but can when installed locally:
```
Cannot find module 'helmet'
Require stack:
- /app/node_modules/koa-helmet/lib/koa-helmet.js
- /app/build/app.js
```

I am sorry to not have anything more specific, but this is all I've managed to gather.