[Bug]: Dereferencing NULL when using an undefined battery animation

[d4ilyrun]

Checklist

• I have read the appropriate section in the contributing guidelines
• I believe this issue is a problem with polybar itself and not a misconfiguration on my part
• I have searched for other open and closed issues that may have already reported this problem
• I have checked the known issues page for this problem.
• I have followed the debugging guide to narrow down the problem to a minimal config.

Steps to reproduce

1. Do not define the content of discharging_label
2. Use the discharging_animation label inside a format field
3. polybar -c <bar_config>

Minimal config

[module/battery]
adapter=ACAD
animation-charging-0=
animation-charging-1=
animation-charging-2=
animation-charging-3=
animation-charging-4=
animation-charging-framerate=750
animation-low-0=
animation-low-1=" "
animation-low-framerate=200
battery=BAT1
format-charging=<animation-charging> <label-charging>
format-charging-foreground=#89DCEB
format-charging-underline=#89DCEB
format-discharging=<ramp-capacity> <label-discharging>
format-discharging-foreground=#89DCEB
format-discharging-underline=#89DCEB
format-full= <label-full>
format-full-foreground=#89DCEB
format-full-underline=#89DCEB
format-low=<animation-discharging> <label-low>
full-at=99
label-charging=%percentage%%
label-discharging=%percentage%%
label-full=Full
label-low=BATTERY LOW
label-low-foreground=#F28FAD
label-low-underline=#F28FAD
low-at=15
ramp-capacity-0=
ramp-capacity-1=
ramp-capacity-2=
ramp-capacity-3=
ramp-capacity-4=
type=internal/battery

Polybar log

polybar|notice:  Parsing config file: /home/leo/.config/polybar/config.ini
polybar|notice:  Listening for IPC messages (PID: 31614)
polybar|notice:  Loading module 'nixos' of type 'custom/text'
polybar|notice:  Loading module 'i3' of type 'internal/i3'
polybar|error: Disabling module "i3" (reason: No built-in support for 'internal/i3')
polybar|notice:  Loading module 'xwindow' of type 'internal/xwindow'
polybar|notice:  Loading module 'mpris-tail' of type 'custom/script'
polybar|notice:  Loading module 'kb' of type 'internal/xkeyboard'
polybar|warn:  The config parameter `module/kb.label-indicator` is deprecated, use `module/kb.label-indicator-on` instead.
polybar|notice:  Loading module 'pulseaudio' of type 'internal/pulseaudio'
polybar|error: Disabling module "pulseaudio" (reason: No built-in support for 'internal/pulseaudio')
polybar|error: Disabling module "alsa" (reason: Missing section "module/alsa")
polybar|notice:  Loading module 'battery' of type 'internal/battery'
polybar|notice:  Loading module 'wireless-network' of type 'internal/network'
polybar|notice:  Loading module 'filesystem' of type 'internal/fs'
polybar|notice:  Loading module 'date' of type 'internal/date'
polybar|notice:  Loaded 8 modules
polybar|notice:  Loaded font "Iosevka:size=13" (name=Iosevka, offset=1, file=/nix/store/z584w3rd81mfigbr8m3v06kyv21dh7wm-home-manager-path/share/fonts/truetype/iosevka-regular.ttf)
polybar|notice:  Loaded font "Iosevka:size=6" (name=Iosevka, offset=1, file=/nix/store/z584w3rd81mfigbr8m3v06kyv21dh7wm-home-manager-path/share/fonts/truetype/iosevka-regular.ttf)
polybar|notice:  Loaded font "Unifont:style=Regular,Regular:size=13" (name=Unifont, offset=0, file=/nix/store/z584w3rd81mfigbr8m3v06kyv21dh7wm-home-manager-path/share/fonts/opentype/unifont.otf)
polybar|notice:  Loaded font "Font Awesome 5 Free Solid:style=Solid:size=12" (name=DejaVu Sans, offset=0, file=/nix/store/7370cbzds0g83pn2v298ksq39xprnrhj-dejavu-fonts-2.37/share/fonts/truetype/DejaVuSans.ttf)
polybar|notice:  Loaded font "Font Awesome 5 Brands Regular:style=Regular:size=12" (name=DejaVu Sans, offset=0, file=/nix/store/7370cbzds0g83pn2v298ksq39xprnrhj-dejavu-fonts-2.37/share/fonts/truetype/DejaVuSans.ttf)
polybar|notice:  Loaded font "Material Design Icons:style=Solid:size=13" (name=Material Design Icons, offset=0, file=/nix/store/z584w3rd81mfigbr8m3v06kyv21dh7wm-home-manager-path/share/fonts/truetype/materialdesignicons-webfont.ttf)
polybar|notice:  Loaded font "Fira Code Nerd Font:style=Retina,Regular:size=13" (name=FiraCode Nerd Font, offset=0, file=/nix/store/z584w3rd81mfigbr8m3v06kyv21dh7wm-home-manager-path/share/fonts/truetype/NerdFonts/FiraCodeNerdFont-Retina.ttf)
polybar|notice:  Loaded font "Font Awesome 5 Free Regular:style=Solid:size=12" (name=DejaVu Sans, offset=0, file=/nix/store/7370cbzds0g83pn2v298ksq39xprnrhj-dejavu-fonts-2.37/share/fonts/truetype/DejaVuSans.ttf)
polybar|warn:  Ignoring unsupported wm-restack option 'i3'

fish: Process 31614, './result/bin/polybar' from job 3, './result/bin/polybar'
terminated by signal SIGSEGV (Address boundary error)

Expected behavior

• Print an error when using a field that is not defined
• Use a default format (doesn't seem to be possible when reading the code)

Actual behavior

Segfaults when calling m_discharging_animation->get() inside battery_module::build

Window Manager and Version

i3 version 4.22 (2023-01-02)

Linux Distribution

NixOs 23.11.20231101.d64dbf7 (Tapir)

Polybar version

polybar 3.6.3

Features: +alsa -curl -i3 -mpd +network(libnl) -pulseaudio +xkeyboard

X extensions: +randr (+monitors) +composite +xkb +xrm +xcursor

Build type: Release
Compiler: /nix/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-gcc-wrapper-12.3.0/bin/g++
Compiler flags:  -O3 -DNDEBUG -Wall -Wextra -Wpedantic -Wsuggest-override
Linker flags:  -Wall -Wextra -Wpedantic -Wsuggest-override  -Wall -Wextra -Wpedantic -Wsuggest-override

Additional Context / Screenshots

No response

[patrick96]

Huh, turns out our validation code that you don't use invalid tags in formats just doesn't work.

The module shouldn't even start because you can't use <animation-discharge> in format-low.

I have fixed this in #3045 and it should be in the 3.7.1 release soon

[d4ilyrun]

Nice ! Thanks a lot 😄