Multiple different errors.

User uses the thrive spell for their farm, as well as uses it on the ground.

Error logs:

https://pastebin.com/juJf7pad

https://pastebin.com/dCdC4nSK

Can you post the rest of the log too? There's other useful stuff in there for figuring out the issue

I ran into this today on the Heavens of Sorcery mod pack.
Minecraft 1.12.2 and wizardry 0.11.1

The server hung in this crash report and the player who has a thrive spell in a belt was kicked when trying to remove it in this full server log.

I'm going to take a random guess that said client had a Thrive Spell of like 10+ power? I'm playing on version 0.11.0 on the Levitated mod pack and decided to make a perfected nacre pearl with Self->Zone(Area=2)->Thrive(Power=10) and what essentially happens is I start it, tps decides to drop down to 1, and every 20 or so seconds you see one use of the spell activate. In between any messages you type in chat are frozen until said spell activation.