Certain TypeScript definitions are not recognised by `react-scripts` in Yarn PnP mode

[gausie]

Describe the bug

Certain TypeScript definitions are just not recognised in processes spawned by react-scripts, while the rest work fine. VSCode thinks the definitions are present (and I can drill down into them using intellisense) and yarn run tsc compiles fine, so I do think this is somehow introduced by react-scripts, probably by Webpack.

The ones I've noticed are:

• @types/loadable__components
• @types/styled-system__theme-get
• @redux-saga/types

Steps to reproduce

1. Make a CRA typescript project
2. Convert to Yarn PnP
3. Install @loadable/component and @types/loadable__component
4. Try to import @loadable/component

Expected behavior

It builds or runs successfully

Actual behavior

TypeScript thinks that no types exist for @loadable/component

Reproducible demo

See: https://github.com/gausie/reproduce-cra-pnp-ts-bug

[gausie]

I found that I was able to get it to work by unplugging @types/loadable__component and wrapping the contents in declare module "@loadable__component" { ... }. No idea why the react-scripts webpack config needs this

[gausie]

AHHA! This is from ts-pnp and is reported upstream (arcanis/ts-pnp#7)

Sadly, it looks like that project is currently unmaintained

[gausie]

Ok I've fully looked into this now and ts-pnp is unmaintained because it's redunant as yarn patches TypeScript for pnp. This should be fixed if we update to the latest fork-ts-checker-webpack-plugin