Versions: Forge 2099, HarvestFestival 0.5.10
With any other mods: false

The game crashes when you open the world previously has a hopper inserting items into a shipping box.
How to reproduce:

1. Create a world.
2. Place a shipping box.
3. Place a hopper pointing the shipping box.
4. Put some items in the hopper. (I put 3 stacks of breads when testing this issue)
5. Save and exit the world.
6. Close the game.
7. Start the game, open the world, and the game crashed.

Here is the crash report: crash-2016-10-17_12.37.52-server.txt

This issue was found in Harvest Festival 0.5.9 by my friend, I tested this in a clean install of version 0.5.10.