Note directly related to our project template, but still a common issue worth documenting.

Many have reported problems with node-sass and the latest NodeJS version. Root cause and its solution seem to be dlmanning/gulp-sass#748

Another issue seems to be stray caches. To ensure that npm or yarn installs the latest versions of everything, these tips might help:

rm -rf node_modules .cache-loader package-lock.json yarn.lock
npm cache clean -f
npm install

These might also sometimes help:

npm --depth 9999 update
npm rebuild

Note, that you might also get different results with npm install X and yarn add X in some corner cases, even though they in principle obey the same package.json