This update fixes a long standing bug that would cause GuiInventories to be unregistered automagically if 3 conditions were met:

1. GuiLib runs on CraftBukkit or Spigot (not on Paper).
2. The InventoryType of the gui is of a tile entity (not chest).
3. A garbage collection sweep happens while the gui was still in memory.

These conditions were very rare, but still, this bug is fixed now.