node-fetch currently completely ignoring Content-Length header while consuming response.
Fetch specification about handling Content-Length on server response says almost nothing:
https://fetch.spec.whatwg.org/#concept-http-network-fetch (see whatwg/fetch#67)

On other hand, we have a fetch-node specific extension to limit the size of the response.

My prop

For improved readability, change:

Object.assign(settings, options);

to:

const settings = { ...defaults, ...options };