Refactor npmPackagesExists() function

[styfle]

What kind of change does this PR introduce?
Refactoring npmPackagesExists() function

Did you add tests for your changes?
No, there is no API change

If relevant, did you update the documentation?
No

Summary

This makes the code more readable and avoids checking the boolean twice

Does this PR introduce a breaking change?
No

Other information

[evenstensberg]

This might have pitfalls, cause maybe we try to resolve the local one later. Putting this on chill for a bit

[webpack-bot]

@styfle Thanks for your update.

I labeled the Pull Request so reviewers will review it again.

@ematipico Please review the new changes.

[ematipico]

@ev1stensberg could you explain? I don't see how: an error is always thrown

[evenstensberg]

The initial idea is to run this on multiple packages, so you can combine different scaffolds. I don't know if it still works ( might need some tweaking ).

How is this handled now? How is the error thrown? I think we got a setup for it. We need to look at potential errors this might raise.

[webpack-bot]

Thank you for your pull request! The most important CI builds succeeded, we’ll review the pull request soon.

[evenstensberg]

lgtm for now, as we only support one package not array of packages to scaffold. We should change the API to support arrays better in the future