This happens if the first time you run NPM it's with sudo, for example when trying to do an npm install -g.
The cache folders need to be owned by the current user, not root.
sudo chown -R $USER:$GROUP ~/.npm
sudo chown -R $USER:$GROUP ~/.config
This will give ownership to the above folders when running with normal user permissions (not as sudo).
It's also worth noting that you shouldn't be installing global packages using SUDO. If you do run into issues with permissions, it's worth changing your global directory. The docs recommend:
mkdir ~/.npm-global
npm config set prefix '~/.npm-global'
Then updating your PATH in wherever you define that (~/.profile etc.)
export PATH=~/.npm-global/bin:$PATH
You'll then need to make sure the PATH env variable is set (restarting terminal or using the source command)
https://docs.npmjs.com/resolving-eacces-permissions-errors-when-installing-packages-globally