Resolve symlinks in Webpack

[adroitwhiz]

Resolves

Resolves #4965

Proposed Changes

This removes resolve {symlinks: false} from the Webpack configuration.

Reason for Changes

This allows Webpack to pick up on changes to npm linked Scratch modules and live-recompile + reload them. While the documentation says the "resolve symlinks" option "may cause module resolution to fail when using tools that symlink packages (like npm link)", it is unclear whether enabling or disabling it causes the failure, and in my case it only worked properly when set to true.

My development environment is Linux-based, so I'm not sure how this affects other OSes.

[thisandagain]

/cc @paulkaplan @rschamp @benjiwheeler

[rschamp]

When #2012 went in, and we didn't have this option, we couldn't build at all while linked, and got errors like:

    Module build failed: ReferenceError: Unknown plugin "react-intl" specified in "base" at 3, attempted to resolve relative to "/Users/rschamp/Documents/Scratch/scratch-audio/src"
        at /Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/file/options/option-manager.js:180:17
        at Array.map (native)
        at Function.normalisePlugins (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/file/options/option-manager.js:158:20)
        at OptionManager.mergeOptions (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/file/options/option-manager.js:234:36)
        at OptionManager.init (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/file/options/option-manager.js:368:12)
        at File.initOptions (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/file/index.js:212:65)
        at new File (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/file/index.js:135:24)
        at Pipeline.transform (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-core/lib/transformation/pipeline.js:46:16)
        at transpile (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-loader/lib/index.js:50:20)
        at Object.module.exports (/Users/rschamp/Documents/Scratch/scratch-gui/node_modules/babel-loader/lib/index.js:173:20)
     @ ./src/containers/gui.jsx 11:20-44
     @ ./src/playground/index.jsx
     @ multi (webpack)-dev-server/client?http://0.0.0.0:8601 ./src/playground/index.jsx

Since that's much more disruptive than live rebuilding not working, I'm currently not inclined to merge this. First I'm going to do some testing with this branch to see if I can reproduce that issue though.

[rschamp]

I don't see the same errors as I had been seeing, so I think this may be merge-able. I will investigate a bit more first.

[rschamp]

I confirmed that one of the members of our team would see errors if they tried to build with a package linked and this option removed, so unfortunately I don't think we should merge this.

I wanted to suggest that you use a CLI option, but it looks like they provide a way to set every resolve option from the command line except symlinks :(

Thanks for your patch though! We should revisit this when it's more certain nobody is using npm < 6.