Nullish assignment (??=) not working in new project

Typescript 4 supports the nullish assignment operator (??=). Creating a new Typescript project with CRA 4 supports this operator in the editor, but when running yarn start it gives a Webpack parsing error.

I asked on SO here and they confirm the bug and suggest it requires a Babel upgrade.

Steps to reproduce:

1. Create a new project with Typescript
2. Add the following lines into App.tsx:

const test = { a: 1 };
test.a ??= 2;

1. Run yarn start

Expected result: App starts

Actual result:

Module parse failed: Unexpected token (14:10)
File was processed with these loaders:
 * ./node_modules/@pmmmwh/react-refresh-webpack-plugin/loader/index.js  
 * ./node_modules/babel-loader/lib/index.js
You may need an additional loader to handle the result of these loaders.

[razzfox]

This is possibly now resolved.

[kellengreen]

The irony of Nullish Assignment being supported in every browser, but breaking via the very thing that’s meant to make future proofing codebases easier.