CobbleStacker

The crash was caused by a rare timing issue — when the server was processing item stacks, another mod or the game itself could add or remove entities at
the same time. This corrupted the internal list Minecraft uses to track entities, causing the server to crash.

We fixed it by making the plugin work on a safe copy of the entity list instead of the live one, so it can't be affected by changes happening at the same time. You shouldn't see this crash anymore.