npmlock2nix fails when a "resolved" field is false in package-lock.json

[tshaynik]

Sometimes, due to a known issue in npm (npm/npm#20106 (comment)), a package-lock.json can be generated where some of the "resolved" fields are false. Running an npmlock2nix on such a package produces an error, as the boolean value false is passed to fetchurl:

error: `url` is not a string

The current workaround is to regenerate the package-lock.json file, using:

rm -rf node_modules
npm cache clean --force
npm install

But I think that npmlock2nix should be able to safely ignore those unresolved dependencies and still run. If that doesn't work, then I think it should fail with a clearer error message.

I'd be happy to try and work on a solution for this. Big thanks to @happysalada for helping me understand this issue!