The Salesforce Lightning Design System uses npm to manage dependencies. Please install Node.js, and try running npm install again.
If Node.js is already installed, make sure you’re running v8 or up.
JavaScript dependencies sometimes get out of sync and inexplicable bugs start to happen. Follow these steps to give a fresh start to your development environment:
- The installed
npmversion must be at least v3.10. You can update your npm with:npm install npm -g(sudomay be required). - Re-install dependencies:
rm -Rf node_modules && npm install npm start
If this did not work, try running npm cache clean and repeat the above steps.