pre-commit uses development ESLint rules rather than prod

[ml-evs]

As noticed by @BenjaminCharmes, the pre-commit ESLint seems to be using the dev rules rather than prod, so some fixable issues are not being fixed automatically. It seems quite hard to set this manually and none of the workarounds I tried seemed to work; instead we might revert the eslint config changes (i.e., treat most things as errors again) but figure out how to get yarn serve to be more forgiving itself.