reloadnpc didn't remove monster spawned by script

[Emistry]

Describe the bug
monster that spawned by NPC script isn't removed.

To Reproduce
Steps to reproduce the behavior:

1. Load the NPC script

testmap,50,50,5	script	EmistyRO	4_F_KAFRA1,{
	end;
	
	OnInit:
		monster("testmap", 0, 0, "Poring", PORING, 1, strnpcinfo(3)+"::OnInit");
		end;
}

2. type @reloadnpc npc\filepath.txt mutiple times.

gm use @reloadnpc npc/filepath.txt
[Info]: HCP: File unloaded. Be aware that mapflags and monsters spawned directly are not removed.
[Info]: HCP: Script loaded.
[Info]: HCP: '@reloadnpc npc/filepath.txt' was used
gm use @reloadnpc npc/filepath.txt
[Info]: HCP: File unloaded. Be aware that mapflags and monsters spawned directly are not removed.
[Info]: HCP: Script loaded.
[Info]: HCP: '@reloadnpc npc/filepath.txt' was used
gm use @reloadnpc npc/filepath.txt
[Info]: HCP: File unloaded. Be aware that mapflags and monsters spawned directly are not removed.
[Info]: HCP: Script loaded.
[Info]: HCP: '@reloadnpc npc/filepath.txt' was used
gm use @reloadnpc npc/filepath.txt
[Info]: HCP: File unloaded. Be aware that mapflags and monsters spawned directly are not removed.
[Info]: HCP: Script loaded.
[Info]: HCP: '@reloadnpc npc/filepath.txt' was used
gm use @reloadnpc npc/filepath.txt
[Info]: HCP: File unloaded. Be aware that mapflags and monsters spawned directly are not removed.
[Info]: HCP: Script loaded.
[Info]: HCP: '@reloadnpc npc/filepath.txt' was used
gm use @reloadnpc npc/filepath.txt
[Info]: HCP: File unloaded. Be aware that mapflags and monsters spawned directly are not removed.
[Info]: HCP: Script loaded.
[Info]: HCP: '@reloadnpc npc/filepath.txt' was used

Expected behavior
monster that spawned by NPC script shall be removed since its' not permanent mob spawns.

Screenshots

System specs (please complete the following information):

• OS: [e.g. windows 10 version 1809, macOS 10.14]
• Hercules Version [e.g. v2019.08.25]
• Mode: [renewal]
• Packet version: [e.g. 20180620]
• Client type: [e.g. RE]

Plugins used or source modifications
If you are using any plugins besides the ones that come bundled with Hercules,
please enumerate them here.

Additional context
Add any other context about the problem here. If the bug report is about a
crash, please attach the core/stack-dump or crash-log, if any.