Furnace and coal bug.

Good evening, I would like to bring this problem to the attention of the staff in 16w39a/b snapshot. The problem is preventing the proper use of the furnace when you want to enter the coal in it the launcher crashes. I tried to drag the unit of coal manually, using the shift and attempted to enter the material with the aid of a hopper, but as soon as the fuel (coal but in this case, I tested that happens with every "burnable" material) enters into the slot to him predetermined the game closes. I hope I was helpful despite my bad English, I'm Italian and I attended a school where the language was not taught.