### Website or app

https://github.com/facebook/react/tree/main/packages/react-devtools-extensions

### Repro steps

Follow the instructions here to build local version of react devtools extension: https://github.com/facebook/react/tree/main/packages/react-devtools-extensions

```
git clone https://github.com/facebook/react.git 
cd react
yarn install
yarn build-for-devtools
```

Stuck on this step everytime `yarn build-for-devtools`:
```
D:\Other\react\node_modules\flow-parser\flow_parser.js:807
throw a}function
^

Error: SignedSource.signFile(...): Cannot sign file without token: <<SignedSource::*O*zOeWoEQle#+L!plEphiEmie@IsG>>
    at Object.<anonymous> (D:\Other\react\node_modules\signedsource\index.js:20:28)
    at Module._compile (node:internal/modules/cjs/loader:1196:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1250:10)
    at Module.load (node:internal/modules/cjs/loader:1074:32)
    at Function.Module._load (node:internal/modules/cjs/loader:909:12)
    at Module.require (node:internal/modules/cjs/loader:1098:19)
    at require (node:internal/modules/cjs/helpers:108:18)
    at Object.<anonymous> (D:\Other\react\scripts\rollup\packaging.js:18:37)
    at Module._compile (node:internal/modules/cjs/loader:1196:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1250:10)
```

Is there anything else I need to set up in order to make this work?

### How often does this bug happen?

Every time

### DevTools package (automated)

_No response_

### DevTools version (automated)

_No response_

### Error message (automated)

_No response_

### Error call stack (automated)

_No response_

### Error component stack (automated)

_No response_

### GitHub query string (automated)

_No response_
if (!existsSync('build/node_modules')) {
    
    return;
  }
  const builtPackageFolders = readdirSync('build/node_modules').filter(
    dir => dir.charAt(0) !== '.'
  );
  await Promise.all(builtPackageFolders.map(prepareNpmPackage));
}
module.exports = {
  copyAllShims,
  getPackageName,
  getBundleOutputPath,
  prepareNpmPackages,
};