My VPN stopped working so I can only message here.
The current final enemy never dies. Its HP just goes into minus numbers, and also its name doesn't change. It still says King Crab, or at least it does for me. This could be due to the fact that I was already past the final page and the enemy was automatically being fought without ever actually having come across it.
I noticed that when upgrading my Blacksmith, I went into negative numbers with coal. After a restart which didn't save my progress, I clicked repeatedly to find out at what point it allows me to buy the upgrade. The price was 4.9k Coal and when it let me buy it, I was left with -0.674k Coal. No idea if this always happens at around 14% under the selling price. Probably be easier for you to figure that one out.
