I used Chain Lightning (on my offhand) while holding a Loot Piñata sword on my main hand (Looting 11) and the game instantly crashed.

It doesn't happen with any other mob AFAIK, just this random fish that my lightning bounced off to. This is the third time this happens and all three were related to a fish on the corner of my screen exploding with loot and everything immediately crashing.

After trying to reproduce bug on single player, it does not occur. It seems to be a server-only issue and the only extra mod on the server is Botany Pots Tiers.

Seems to be an interaction between Loot Piñata and Non-stackable items dropping from aquaculture fishes.