Refactor map modules

[jsnanigans]

Proposed changes

use chunk.modules.map instead of chunk.mapModules

Types of changes

• Bugfix (non-breaking change which fixes an issue)

Checklist

• Lint and unit tests pass locally with my changes

Further comments

This should fix the issues
#11
and
FullHuman/purgecss#46

I used the webpack documentation as reference
https://webpack.js.org/contribute/plugin-patterns/#exploring-assets-chunks-modules-and-dependencies

[Ffloriel]

I don't think using chunk.modules is the solution. The issue #1 reappears.
running the tests, I see the deprecation warning:

(node:2001) DeprecationWarning: Chunk.modules is deprecated. Use Chunk.getNumberOfModules/mapModules/forEachModule/containsModule instead.

[jsnanigans]

Maybe the issue stems from no modules being present.. I'll test this tomorrow

[jsnanigans]

@Ffloriel or how about we keep chunk.mapModules but just check if the function exists first..
something like this:

chunk.mapModules ? chunk.mapModules(mod => ...) : []

I think this would remove the error that breaks the build and avoids the deprication warning

[Ffloriel]

I tried to reproduce the issue but with no success.
Ideally, it will be better to reproduce the issue to be sure it is fixed but that seems to be a good temporary solution.