Returns execflow control to cache enabled webpack on linting error

[nicolaslt]

This is an issue with an ancient version of webpack (1.X). It feels like it also might be one with newer versions.

This PR correctly informs Webpack 1.X that an error has happened. It is only relevant when the cache options is enabled, due to webpack.async().

[jsf-clabot]

All committers have signed the CLA.

[nicolaslt]

I retrofitted some tests. Apologies, those should have been in my initial PR.

[nicolaslt]

Any chance this could have a merge&release?

[MoOx]

Can we find better name for this PR? Would help for release notes. Thanks!
I will merge as soon as I am sure on what is this about (I don't use this module anymore but nobody is maintaining it so, I am trying to help...)

[nicolaslt]

I'm struggling to find a good title. The shortest yet most correct title I can come up with would be: "Fix not returning execution flow control to webpack when cache option is enabled and one of the files has a linting error".

But that's a bit long.

To be fair though, we sinced moved away from using eslint-loader so it's not a pressing matter for us anymore.

[DiscoNova]

struggling to find a good title

I know the struggle; naming things is hard ;)

How about "Returns execflow control to cache enabled webpack on linting error"?

[MoOx]

Thank you!