Hmmm, seems that there is some kind of error in one of my functions (copyMixer), where it's trying to do something to a value that doesn't exist. That function is supposed to copy an existing metal mixing furnace, and turn it into a mini mixer. Either bobs mods or shinybobgfx have updated and changed something about the metal mixing furnace graphics, or there is some other mod affecting the icons.
I'm currently in the process of rewriting this mod, and I've completely gotten rid of that function, so I'll probably just release the new version, instead of trying to fix the current live version.
Thanks for bringing this to my attention; forces me to stop procrastinating about the update. Hopefully, I should have an update that fixes the issue before next Monday.