Auto Shadow Spell Nullpo Error

[bWolfie]

Describe the bug
Nullpo error when using Auto Shadow Spell skill. Hoping someone can reproduce.

To Reproduce
Steps to reproduce the behavior:

1. Use Auto Shadow Spell.
2. Click cancel or ok without selecting a skill.

Expected behavior
Skill should not trigger nullpo error.

Screenshots

System specs (please complete the following information):

• OS: [CentOS 7]
• Hercules Version [v2024.02]
• Mode: [pre-re]
• Packet version: [20160113]
• Client type: [main]

Plugins used or source modifications
N/A

Additional context
N/A

[guilherme-gm]

I can reproduce it on v2024.03, using 2019-12-24 main.

In my case, I didn't even see the window (maybe I didn't have anything to see). I get a bit different stack:

[Warning]: skill_get_index: skill id '0' is not being handled!
[Error]: --- failed assertion --------------------------------------------
[Error]: skill.c:136: '0' in function `skill_get_index'
[Error]: 0x555948e0fcb1 nullpo_backtrace_print
[Error]:        [redacted]/Hercules/src/common/nullpo.c:77
[Error]: 0x555948e0fdd1 assert_report
[Error]:        [redacted]/Hercules/src/common/nullpo.c:147
[Error]: 0x555948d1e642 skill_get_index
[Error]:        ../map/map.h:136
[Error]: 0x555948d5f15b skill_castend_nodamage_id
[Error]:        ../map/map.h:10449
[Error]: 0x555948d44b10 skill_castend_id
[Error]:        ../map/map.h:6548
[Error]: 0x555948e2298e do_timer
[Error]:        [redacted]/Hercules/src/common/timer.c:498
[Error]: 0x555948e29708 main
[Error]:        [redacted]/Hercules/src/common/core.c:542
[Error]: 0x7faef5395d8f __libc_start_call_main
[Error]:        ../sysdeps/x86/libc-start.c:58
[Error]: 0x7faef5395e3f __libc_start_main_impl
[Error]:        ../sysdeps/nptl/libc_start_call_main.h:392
[Error]: 0x555948a79c54 ???
[Error]:        ???:0
[Error]: 0xffffffffffffffff ???
[Error]:        ???:0
[Error]: --- end failed assertion ----------------------------------------