Fix browser build dev setup

[hwbllmnn]

Description

This fixes the browser build dev setup.

Pull request type

• Bugfix
• Feature
• Dependency updates
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe)
• I am unsure (we'll look into it together)

Do you introduce a breaking change?

• Yes
• No
• I am unsure (no worries, we'll find out)

Checklist

• I understand and agree that the changes in this PR will be licensed under the BSD 2-Clause License
• I have followed the guidelines for contributing
• The proposed change fits to the content of the code of conduct
• I have added or updated tests and documentation, and the test suite passes (run npm test locally)
• I'm lost; why do I have to check so many boxes? Please help!

[KaiVolland]

Can you explain why the MiniCssExtractPlugin causes the problem and removing solves it?

[KaiVolland]

Maybe removing the hmr option is sufficent.

[hwbllmnn]

Maybe removing the hmr option is sufficent.

Perhaps it is, I didn't really analyze the problem. I noticed the dev build was not working any more and then compared the build config with the production browser build file and noticed that the plugin is not present there (at least not in the less section). So I just made sure that both builds work the same (minus the optimizations for prod obviously).

[KaiVolland]

The docs of MiniCssExtractPlugin say that hmr is deprecated for webpack 4. Maybe give it a try. If it's not working we can remove it completly.

[hwbllmnn]

The docs of MiniCssExtractPlugin say that hmr is deprecated for webpack 4. Maybe give it a try. If it's not working we can remove it completly.

Why do you want to keep the plugin in the dev build only? I'd prefer to have the dev build as close to the prod build as possible.

[hwbllmnn]

Also, removing the hmr option does not fix the problem. We get this error for all files:

ERROR in ./src/Component/Symbolizer/SLDRenderer/SLDRenderer.less
Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):
ReferenceError: document is not defined