I had posted previously that this plugin was not working for me. So, for any of you running 1.12.2 Spigot, if this doesn't work for you and your console is reading out cannot pass event (event) to (npc/sign/chest), downgrade to version 2.5 in the Version History Tab.
NOTE TO THE DEV:
Keep up the good work! I love your plugin and am contemplating purchasing the full version or at least donating to you! One thing, please fix the issue stated above if at all possible. I am happy to provide more details if you need it.