I have cloned the project and did install all dependencies from the root directory using npm install then as a part of testing I did move to /examples/testing-dom__drag-drop (cd ./examples/testing-dom__drag-drop) and executed npm start(screenshot1) command to start the localhost, but it gave me an error(screenshot2):
screenshot1:

screenshot2:

Node version: 12.14.0
NPM version: 6.13.4
Is there something I am missing?