To fix a bug, I had to implement the sorter automatically turns off when trying to add sort-able resources to a furnace that is on and has Sorter turned on.
As the attached image shows, if you add to a Furnace that is turned on and has sorter on, sorter will automatically disable to prevent attempting to stack an invalid stack.
This issue only occurs when a stack disappears the instant Sorter is trying to modify the stack size but nonetheless I was able to duplicate the issue and if someone loses a stack of ore they are going to be pissed.
I also matched the color of the button with the existing furnace On/Off colors
Hoping to release an "Optimization" feature soon which will remove excess ore or wood not required to smelt the current contents. More to come as I near release.