rxjs/Subject.d.ts error : Class 'Subject' incorrectly extends base class 'Observable'

Question

I extracted sample template code from this tutorial and did below two steps to get started -

1. npm install // worked fine and created node_modules folder

Answer 1

yes the problem was with TypeScript 2.4.1 I just uninstalled this from Control panel and it works for me as Visual Studio 2017 already has this.