Issue: Smelter takes up to 2 material pieces, but outputs whatever amount was entered
Say, you put 10 ore chunks in smelter and try to heat up and smelt all 10 of them.
Smelting progress shows -8 / 1 Smelting %
After smelting is done you have 8 ore chunks inside and 10 ingots of output.
Works fine if you smelt no more than 2 at a time