@WhiteNoise Thanks for the response. It did happen again, and the error I see in the console is Uncaught (in promise) Error: ENOSPC: System limit for number of file watchers reached, watch '/home/hassan/Dropbox/notes/'.
I suppose that error message is clear enough. I was able to solve it by running:
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
I hope that helps you fix the bug. If you need anything else from me, please let me know.