Take coal out of furnace a sometime crah
Comments 2
Crashes are hard to reproduce, but this particular one has bitten me so often that I've learned to always Quit to Title before interacting with a furnace, especially if I've invested a lot of work since the last save. The crash happens most often when you do multiple interactions with a furnace at one time. (Example: put something in either input bin; change your mind and take it back out; switch to the other bin; put something in; switch back to the first bin; put something in; etc., all without closing the furnace.) But sometimes the crash happens on the first tap, even if all you're doing is removing the product.
Again, do not report crashes if you have no way to reproduce.