It doesn't have to be. Mine is ./src/client.js for example If you want zero config then there are assumptions it makes, but that's true of all zero config setu

It doesn't have to be. Mine is ./src/client.js for example If you want zero config then there are assumptions it makes, but that's true of all zero config setups - they assume defaults. Changing it is one property in a config file. Not exactly tricky or complex.