If you are running ArchLinux, run the following command instead (see here for why):
echo fs.inotify.max_user_watches=524288 | sudo tee /etc/sysctl.d/40-max-user-watches.conf && sudo sysctl --system
Then paste it in your terminal and press on enter to run it.
Source: https://github.com/guard/listen/wiki/Increasing-the-amount-of-inotify-watchers