Silly segfault with debug hooks that error and the visible_itemwield mod

[TheEt1234]

Luanti version

Luanti 5.15.1 (Linux)
Using LuaJIT 2.1.1767980792
Built by GCC 15.2
Running on Linux/6.19.13 x86_64
BUILD_TYPE=Release
RUN_IN_PLACE=0
USE_CURL=1
USE_GETTEXT=1
USE_SOUND=1
STATIC_SHAREDIR="/usr/share/luanti"
STATIC_LOCALEDIR="/usr/share/locale"

Operating system and version

arch btw

CPU model

No response

GPU model

No response

Active renderer

No response

Summary

When having the visible_wielditem mod enabled and doing //lua debug.sethook(error, "c") with debug hooks, this happens:

2026-04-25 22:33:39: ACTION[Server]: [log] Caught command '/lua', issued by 'singleplayer'. Parameters: 'debug.sethook(error,"c")'
2026-04-25 22:33:39: ERROR[Main]: ServerError: AsyncErr: Lua: Runtime error from mod 'worldedit_shortcommands' in callback on_chat_message(): /usr/share/luanti/builtin/common/misc_helpers.lua:120: call
2026-04-25 22:33:39: ERROR[Main]: stack traceback:
2026-04-25 22:33:39: ERROR[Main]: 	[builtin#19]: at 0x7f458d1d6ed0
2026-04-25 22:33:39: ERROR[Main]: 	/usr/share/luanti/builtin/common/misc_helpers.lua:120: in function 'dump'
2026-04-25 22:33:39: ERROR[Main]: 	/home/et/.minetest/mods/worldedit/worldedit/code.lua:27: in function 'lua'
2026-04-25 22:33:39: ERROR[Main]: 	.../et/.minetest/mods/worldedit/worldedit_commands/code.lua:24: in function 'func'
2026-04-25 22:33:39: ERROR[Main]: 	.../et/.minetest/mods/worldedit/worldedit_commands/init.lua:53: in function 'run'
2026-04-25 22:33:39: ERROR[Main]: 	.../et/.minetest/mods/worldedit/worldedit_commands/init.lua:61: in function 'func'
2026-04-25 22:33:39: ERROR[Main]: 	/usr/share/luanti/builtin/game/chat.lua:79: in function </usr/share/luanti/builtin/game/chat.lua:50>
2026-04-25 22:33:39: ERROR[Main]: 	/usr/share/luanti/builtin/common/register.lua:27: in function </usr/share/luanti/builtin/common/register.lua:13>
2026-04-25 22:33:40: ACTION[ServerStop]: Server: Shutting down
2026-04-25 22:33:40: ERROR[ServerStop]: ModError while shutting down: Runtime error from mod 'worldedit_shortcommands' in callback on_shutdown(): /usr/share/luanti/builtin/common/register.lua:13: call
2026-04-25 22:33:40: ERROR[ServerStop]: stack traceback:
2026-04-25 22:33:40: ERROR[ServerStop]: 	[builtin#19]: at 0x7f458d1d6ed0
2026-04-25 22:33:40: ERROR[ServerStop]: 	/usr/share/luanti/builtin/common/register.lua:13: in function </usr/share/luanti/builtin/common/register.lua:13>
2026-04-25 22:33:40: ERROR[ServerStop]: Check debug.txt for details.
2026-04-25 22:33:40: ERROR[ServerStop]: ModError while shutting down: Runtime error from mod 'visible_wielditem' in callback luaentity_Deactivate(): /home/et/.minetest/mods/visible_wielditem/init.lua:158: call
2026-04-25 22:33:40: ERROR[ServerStop]: stack traceback:
2026-04-25 22:33:40: ERROR[ServerStop]: 	[builtin#19]: at 0x7f458d1d6ed0
2026-04-25 22:33:40: ERROR[ServerStop]: 	/home/et/.minetest/mods/visible_wielditem/init.lua:158: in function </home/et/.minetest/mods/visible_wielditem/init.lua:158>
2026-04-25 22:33:40: ERROR[ServerStop]: Check debug.txt for details.
2026-04-25 22:33:49: WARNING[ServerStop]: server::ActiveObjectMgr::~ActiveObjectMgr(): not cleared.
Error: nu::shell::core_dumped

This may not be exclusive to that mod, but i have managed to reproduce the issue with it

Steps to reproduce

1. Have the visible_wielditem mod (https://content.luanti.org/packages/LMD/visible_wielditem/)
2. run //lua debug.sethook(error, "c")
3. luanti should segfault

[appgurueu]

luanti/src/server.cpp

Lines 413 to 418 in 4d3ca7c

	try {
	// Empty out the environment, this can also invoke callbacks.
	m_env->deactivateBlocksAndObjects();
	} catch (ModError &e) {
	addShutdownError(e);
	}

This may still run Lua code after a "fatal" Lua error has occurred. So inside on_deactivate of visible_wielditem, another error is thrown and that messes things up, presumably because deactivation is aborted (hence the warning about the AO manager not being cleared, for example).

What's maybe interesting here is that will happen twice here: Once when on_shutdown callbacks are run, another time when on_deactivate is run. Hence you get it for worldedit_shortcommands and visible_wielditem.

Likely related: #8352

[cx384]

Seems like the ScriptApiEntity got messed up such that ActiveObjectMgr.clear() doesn't work anymore.
AddressSanitizer output:

==10012==ERROR: AddressSanitizer: SEGV on unknown address 0x0000000001e8 (pc 0x5630d956378d bp 0x7bcc1e9c0940 sp 0x7bcc1e9c0840 T28)
==10012==The signal is caused by a READ memory access.
==10012==Hint: address points to the zero page.
    #0 0x5630d956378d in ScriptApiEntity::luaentity_Remove(unsigned short) .../luanti/src/script/cpp_api/s_entity.cpp:111
    #1 0x5630d96f9c9e in LuaEntitySAO::~LuaEntitySAO() .../luanti/src/server/luaentity_sao.cpp:93
    #2 0x5630d96f9edf in LuaEntitySAO::~LuaEntitySAO() .../luanti/src/server/luaentity_sao.cpp:99
    #3 0x5630d94e3dc0 in std::default_delete<ServerActiveObject>::operator()(ServerActiveObject*) const /usr/include/c++/15.2.1/bits/unique_ptr.h:92
    #4 0x5630d94e1f9e in std::unique_ptr<ServerActiveObject, std::default_delete<ServerActiveObject> >::~unique_ptr() /usr/include/c++/15.2.1/bits/unique_ptr.h:398
    #5 0x5630d96a460c in ModifySafeMap<unsigned short, std::unique_ptr<ServerActiveObject, std::default_delete<ServerActiveObject> > >::remove(unsigned short const&) .../luanti/src/server/../util/container.h:462
    #6 0x5630d969e816 in server::ActiveObjectMgr::removeObject(unsigned short) .../luanti/src/server/activeobjectmgr.cpp:100
    #7 0x5630d96a29b9 in ActiveObjectMgr<ServerActiveObject>::clear() .../luanti/src/activeobjectmgr.h:41
    #8 0x5630d969d701 in server::ActiveObjectMgr::~ActiveObjectMgr() .../luanti/src/server/activeobjectmgr.cpp:18
    #9 0x5630d9c38f25 in ServerEnvironment::~ServerEnvironment() .../luanti/src/serverenvironment.cpp:313
    #10 0x5630d9c38fd3 in ServerEnvironment::~ServerEnvironment() .../luanti/src/serverenvironment.cpp:313
    #11 0x5630d9bb9d5a in Server::~Server() .../luanti/src/server.cpp:428
    #12 0x5630d9bba993 in Server::~Server() .../luanti/src/server.cpp:466
    #13 0x5630d8e85211 in operator() .../luanti/src/client/game.cpp:664

[sfan5]

Seems like the ScriptApiEntity got messed up

It's simply already deallocated.
We should fix such crashes, but it's not important or feasible to gracefully handle all ways the user can shoot himself in the foot using Lua.