[BUG] Crash upon pressing PageDn in Options/General

[BGazotti]

Describe the bug
Pressing Page Down in the [general] options screen will cause a crash with ERROR: Exception in main loop -> unordered_map::at and exit code 1.

To Reproduce
Open btop.
Press O to open the options menu.
Press Page Down.

Note: switching to another submenu and pressing PageDn will not lead to a crash.

Expected behavior

The list should roll down to the next page.

Screenshots
Not applicable.

Info:
btop version: 1.4.0
Compiled with: x86_64-pc-linux-gnu-g++ (14.2.1)
Configured with: cmake -DBTOP_STATIC=false -DBTOP_USE_MOLD=false -DBTOP_FORTIFY=false -DBTOP_GPU=true

• Binary: built from the Gentoo repositories with C(XX)FLAGS="-march=x86-64-v3 -Og -ggdb3"
• Architecture: x86_64
• Platform: Linux
• (Linux) Kernel: 6.12.9-gentoo-custom-bmq
• Terminal used: kitty
• Font used: Ubuntu Mono Bold 12

Additional context

Contents of ~/.config/btop/btop.log: same as stdout.

2025/01/21 (16:48:13) | ===> btop++ v.1.4.0                                                                                     
2025/01/21 (16:48:13) | DEBUG: Running in DEBUG mode!                                                                           
2025/01/21 (16:48:13) | INFO: Logger set to DEBUG                                                                               
2025/01/21 (16:48:13) | DEBUG: Using locale en_GB.utf8                                                                          
2025/01/21 (16:48:13) | INFO: Running on /dev/pts/0                                                                             
2025/01/21 (16:48:13) | INFO: Failed to load libnvidia-ml.so, NVIDIA GPUs will not be detected: libnvidia-ml.so.1: cannot open shared object file: No such file or directory                                                                                    
2025/01/21 (16:48:13) | WARNING: ROCm SMI: Failed to get maximum GPU temperature, defaulting to 110°C                           
2025/01/21 (16:48:13) | WARNING: ROCm SMI: Failed to get GPU power usage                                                        
2025/01/21 (16:48:14) | DEBUG: Failed to find Intel GPU sysfs path, Intel GPUs will not be detected                             
2025/01/21 (16:48:14) | DEBUG: Shared::init() : Initialized.                                                                    
2025/01/21 (16:48:17) | ERROR: Exception in main loop -> unordered_map::at                                                      
2025/01/21 (16:48:17) | INFO: Quitting! Runtime: 00:00:04  

GDB Backtrace

Not generated.

[seth-wood]

Submitted a fix #1036