The sass-loader version is too high (10.1.1 used in my previous project).
It can be modified to the following version (there are some problems with other versions below, the following version is the safest):
# Uninstall:
npm uninstall node-sass sass-loader --save-dev
npm install node-sass@4.12.0 --save-dev
npm install sass-loader@8.0.2 --save-dev