Remove old installation (if any) rm -rf ~/.local/share/gnome-shell/extensions/contestcountdown@raghav

Copy the gnome folder to ~/.local/share/gnome-shell/extensions/ and rename it to contestcountdown@raghav

Restart gnome by pressing alt + F2 and typing r in the dialog box. (On wayland you will have to log out and log in)

Enable extension using any extension manager, or with the command gnome-extensions enable contestcountdown@raghav (You only need to do this once)

All logs/errors will be recorded in system log, you can view them with journalctl -f

You can also use looking glass. It is like developer console of gnome. Run it by pressing alt + F2 and typing lg in the dialog box.