The pattern for files to be ignored by git can be defined once for the whole project, at the root. A patter like "node_modules" means that any file - or folder - will be ignore in each sub-folder recursively. The drawback is that now you cannot use files/folders to be included. But who would want to include app/tmp, app/dist app/dist, app/npm-debug.log anyways ?
Also, in chapter 10, the hello world kept a dist/bundle.js, which is generated by webpack. I removed it in favour of building it on demand. It is a consequence of point 1.
Two fixes, again.