I've been trying to update a Create React App to use yarn 2 and plug and play (PNP). When I do use nodeLinker: node-modules in the .yarnrc.yml, I can successfully start the dev-server. Without it, I end up with
./src/App.scss (./.yarn/$$virtual/css-loader-virtual-fe3fa7be11/0/cache/css-loader-npm-3.4.2-300ee159b3-2.zip/node_modules/css-loader/dist/cjs.js??ref--6-oneOf-5-1!./.yarn/cache/postcss-loader-npm-3.0.0-f4ab99b685-2.zip/node_modules/postcss-loader/src??postcss!./.yarn/cache/resolve-url-loader-npm-3.1.1-cf1a268137-2.zip/node_modules/resolve-url-loader??ref--6-oneOf-5-3!./.yarn/unplugged/sass-loader-virtual-14ae4e1150/node_modules/sass-loader/dist/cjs.js??ref--6-oneOf-5-4!./src/App.scss)
Error: A package is trying to access a peer dependency that should be provided by its direct ancestor but isn't
Required package: node-sass (via "node-sass")
Required by: sass-loader@virtual:74ba539c0b6c6c8346ea151c91664bff0bef13782983a6f90ddf1a26160140360771dcf40d0863b46ff7add674bc2c42a37daea25f24f4ea96f7843786460ecd#npm:8.0.2 (via /Users/me/color-contrast-matrix/.yarn/unplugged/sass-loader-virtual-14ae4e1150/node_modules/sass-loader/dist/)
It looks like yarn 2 provides a way of overriding a packages dependencies. You have to provide the missing dependency, at least in this case.
From the docs current link:
Some packages may have been specified incorrectly with regard to their dependencies - for example with one dependency being missing, causing Yarn to refuse it the access. The packageExtensions fields offer a way to extend the existing package definitions with additional information. If you use it, consider sending a PR upstream and contributing your extension to the plugin-compat database.
After installing node-sass and adding this config, compilation succeeded.
# .yarnrc.yml
packageExtensions:
'sass-loader@*':
optionalDependencies:
node-sass: '*'