[BUG] Nice level underflow

[slonkazoid]

Describe the bug

nice level number underflows

To Reproduce

start a process with nice -n -4 and see the nice level from btop

Expected behavior

nice should display -4

Screenshots

Info (please complete the following information):

• btop++ version: 1.2.12
• Binary: Arch official repos
• Architecture: x86_64
• Platform: Linux
• (Linux) Kernel: 6.0.7-zen1-1-zen
• Terminal used: Alacritty
• Font used: Hack Regular 10

Additional context

contents of ~/.config/btop/btop.log

2022/11/06 (12:22:24) | ===> btop++ v.1.2.12
2022/11/06 (12:22:24) | DEBUG: Starting in DEBUG mode!
2022/11/06 (12:22:24) | INFO: Logger set to DEBUG
2022/11/06 (12:22:24) | DEBUG: Setting LC_ALL=en_US.UTF-8
2022/11/06 (12:22:24) | INFO: Running on /dev/pts/2
2022/11/06 (12:22:28) | INFO: Quitting! Runtime: 00:00:04

[aristocratos]

@uAliFurkanY @correabuscar
Good catch, fixed in latest commits.