If you fill a cauldron with water and place a piston behind the cauldron, then power the piston into a comparator, the game may crash before you can pull the lever all the way. Though, if you fill a cauldron with water and take some out of the cauldron with a glass bottle, the game will always crash immediately after pulling the lever. Please fix this bug, it can get very annoying at some points when trying to make redstone machines involving the cauldron with water.