Webpack 2 bug: "ReferenceError: exports is not defined"

[gaearon]

Cross-posting from webpack/webpack#3974 (comment) for visibility.

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I can consistently reproduce this in CRA codebase:

git clone https://github.com/facebookincubator/create-react-app.git
cd create-react-app
git checkout 9e733b57f8ae7ae3df46d95910d255798107448f
npm install

npm start

Then edit packages/react-scripts/template/src/App.js to have an empty block in the render method:

Press save. The browser will reload.

Then edit it to remove the empty block and press save.

You will see the error:

Unfortunately some internal state appears corrupted because even if I refresh the page, I keep getting the broken bundle. It only gets fixed by a restart of the server.

[gaearon]

It looks like a caching issue caused by babel-loader. I probably had some version of the module cached with CommonJS transform applied, and it was getting embedded into the bundle. Deleting node_modules/.cache fixed the issue.

[Timer]

Maybe using #2092 will alleviate future cache problems?

[gaearon]

I would actually expect the opposite effect 😄 Caches are hard.