ACF1: Fix Lua error when hitting Attack after failing the rope challenge "difficulty" variable was falsely set to 0 in this case, but only 1 or 2 are allowed

[package]
name = "lfprng"
version = "0.1.0"
authors = ["Andrey Korotaev <a.korotaev@hedgewars.org>"]
edition = "2018"

[dependencies]