Mistake in chapter 50

[marioferpa]

In the gui.rs fix section the code is:

let health = format!(" HP: {} / {} ", stats.hp, stats.max_hp);

But that doesn't work anymore at that point. It should be:

let health = format!(" HP: {} / {} ", stats.hit_points.current, stats.hit_points.max);

As seen in the finished code.