Minimum reproduceable example of Storybook bug with CommonJS exports?

I'm trying to use Storybook with a react component library bundled with CSS. The component is imported into a regular website at localhost:3000 and displays fine, but the Storybook preview errors with The requested module '/@fs/Users/{user}/mre/packages/react/dist/index.js' does not provide an export named 'MyComponent'

Steps to reproduce

1. Clone this repo
2. Run pnpm install
3. Then pnpm run dev
4. Navigate to http://localhost:3000 and see the component ("Hello Storybook!")
5. Navigate to http://localhost:6006 and select MyComponent to see the error above

Note that in dist/index.js there is this line, which sure looks like an export to me.

exports.MyComponent = MyComponent;