Spent a half hour on the forums trying to solve this one the other day. Then - classic - I forgot what the solution was and spent another half hour again just there.

If you are getting this error “TypeError: this.getOptions is not a function”

You need to:

yarn remove sass-loader
//or npm equivalent: 

npm uninstall sass-loader

And then install version 10 of sass-loader

yarn add sass-loader@10