Can't npm start website

[m4tr1k]

Hi everyone.
I wanted to do some changes on the website (on the sidebar), but I can't npm start the project, cmd gives me error when doing it:

I also tried with bash (on Windows), it runs webpack, but then it gives error again:

When running npm run test, it gives a lot of errors aswell. I don't know how to solve this. I already did some changes on the project, but I don't know if those changes are correct or not. I would like some help on this.