There's one problem with `npm ci`: it deletes the `node_modules` directory, thereby thwarting attempts at caching it between builds. As a workaround, we use `np

There's one problem with `npm ci`: it deletes the `node_modules` directory, thereby thwarting attempts at caching it between builds. As a workaround, we use `npm install` followed by `git diff --quiet package-lock.json`, which will abort the CI process if npm installing changed the lock file (i.e. if someone forgot to commit changes to it after adding a package).