For everyone facing an issue like this one, starting a React application:

Error: ENOSPC: System limit for number of file watchers reached, watch

At first I wanted to disable this file watching, but I realized it was not an easy thing to do, so I followed this approach on https://confluence.jetbrains.com/display/IDEADEV/Inotify+Watches+Limit

More details can be found at https://unix.stackexchange.com/questions/13751/kernel-inotify-watch-limit-reached

As I am using linux, I did was the following:

  1. Add a new .conf file under /etc/sysctl.d and add the following line
fs.inotify.max_user_watches = 524288

2. Then you just need to execute the following command line:

sudo sysctl -p --system