Enter Library project, npm install then npm run build.
Copy library-example-0.0.1.tgz to consumer project. Run npm install and then npm run dev.
Upon page load, an error should appear on console Each child in a list should have a unique "key" prop...
This does not happen if you npm run build:dev (sets process.env.NODE_ENV = development)
Error does not trigger if a random key is added to <Grid> component.