Crash when duplicating instantiated scene that removes child node in _enter_tree

[Pshy0]

Tested versions

Does not happen in 4.3-dev5
Happens in 4.3-dev6

System information

Godot v4.3.dev6 - Ubuntu 23.10 23.10 - X11 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1650 () - Intel(R) Core(TM) i5-10300H CPU @ 2.50GHz (8 Threads)

Issue description

My game crashes with the following error message:

Godot Engine v4.3.dev6.official.64520fe67 - https://godotengine.org
Vulkan 1.3.242 - Forward+ - Using Device #1: NVIDIA - NVIDIA GeForce GTX 1650

ERROR: Index p_index = 7 is out of bounds ((int)data.children_cache.size() = 7).
   at: get_child (scene/main/node.cpp:1684)

================================================================
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.3.dev6.official (64520fe6741d8ec3c55e0c9618d3fadcda949f63)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /lib/x86_64-linux-gnu/libc.so.6(+0x42990) [0x7b67bfc42990] (??:0)
[2] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x429b1a1] (??:0)
[3] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x4871256] (??:0)
[4] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x487132b] (??:0)
[5] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x238816e] (??:0)
[6] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x2334236] (??:0)
[7] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x7e4821] (??:0)
[8] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x6c2be1] (??:0)
[9] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x69abd2] (??:0)
[10] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x4247c9f] (??:0)
[11] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x7d6ec9] (??:0)
[12] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x6c2be1] (??:0)
[13] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x423542f] (??:0)
[14] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x408195f] (??:0)
[15] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x7e2ee4] (??:0)
[16] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x6c2be1] (??:0)
[17] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x423542f] (??:0)
[18] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x408195f] (??:0)
[19] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x7e2ee4] (??:0)
[20] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x6c2be1] (??:0)
[21] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x2318742] (??:0)
[22] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x43c685] (??:0)
[23] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x4216a88] (??:0)
[24] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x2329174] (??:0)
[25] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x23650d3] (??:0)
[26] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x2370790] (??:0)
[27] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x526ab3] (??:0)
[28] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x420042] (??:0)
[29] /lib/x86_64-linux-gnu/libc.so.6(+0x28150) [0x7b67bfc28150] (??:0)
[30] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x89) [0x7b67bfc28209] (??:0)
[31] /home/user/Godot_v4.3-dev6_linux.x86_64() [0x43aaba] (??:0)
-- END OF BACKTRACE --
================================================================

Steps to reproduce

Run the MRP

Minimal reproduction project (MRP)

s11d-gdproj.zip

[akien-mga]

Thanks for making a reproduction project. I can reproduce the bug with it, which should make it easy for contributors to identify what caused the bug and provide a fix.

Backtrace with debug symbols:

ERROR: Index p_index = 0 is out of bounds ((int)data.children_cache.size() = 0).
   at: get_child (./scene/main/node.cpp:1684)

================================================================
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.3.dev.custom_build (d2dcaf4e537fed11fecf8d3b21735b95058180ce)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /lib64/libc.so.6(+0x40710) [0x7f83d1616710] (??:0)
[2] Object::get(StringName const&, bool*) const (/home/akien/Godot/godot/./core/object/object.cpp:318)
[3] Node::_duplicate_properties_node(Node const*, Node const*, Node*) const (/home/akien/Godot/godot/./scene/main/node.cpp:2911 (discriminator 2))
[4] Node::_duplicate_properties_node(Node const*, Node const*, Node*) const (/home/akien/Godot/godot/./scene/main/node.cpp:2933 (discriminator 3))
[5] Node::duplicate(int) const (/home/akien/Godot/godot/./scene/main/node.cpp:2825)
[6] void call_with_variant_args_retc_helper<__UnexistingClass, Node*, int, 0ul>(__UnexistingClass*, Node* (__UnexistingClass::*)(int) const, Variant const**, Variant&, Callable::CallError&, IndexSequence<0ul>) (/home/akien/Godot/godot/./core/variant/binder_common.h:807 (discriminator 1))
[7] void call_with_variant_args_retc_dv<__UnexistingClass, Node*, int>(__UnexistingClass*, Node* (__UnexistingClass::*)(int) const, Variant const**, int, Variant&, Callable::CallError&, Vector<Variant> const&) (/home/akien/Godot/godot/./core/variant/binder_common.h:569)
[8] MethodBindTRC<Node*, int>::call(Object*, Variant const**, int, Callable::CallError&) const (/home/akien/Godot/godot/./core/object/method_bind.h:619 (discriminator 1))
[9] GDScriptFunction::call(GDScriptInstance*, Variant const**, int, Callable::CallError&, GDScriptFunction::CallState*) (/home/akien/Godot/godot/./modules/gdscript/gdscript_vm.cpp:1862 (discriminator 1))
[10] GDScriptInstance::callp(StringName const&, Variant const**, int, Callable::CallError&) (/home/akien/Godot/godot/./modules/gdscript/gdscript.cpp:1981 (discriminator 1))
[11] bool Node::_gdvirtual__ready_call<false>() (/home/akien/Godot/godot/./scene/main/node.h:354 (discriminator 1))
[12] Node::_notification(int) (/home/akien/Godot/godot/./scene/main/node.cpp:214)
[13] Node::_notificationv(int, bool) (/home/akien/Godot/godot/./scene/main/node.h:49 (discriminator 14))
[14] CanvasItem::_notificationv(int, bool) (/home/akien/Godot/godot/./scene/main/canvas_item.h:45 (discriminator 3))
[15] Node2D::_notificationv(int, bool) (/home/akien/Godot/godot/./scene/2d/node_2d.h:37 (discriminator 3))
[16] Object::notification(int, bool) (/home/akien/Godot/godot/./core/object/object.cpp:907)
[17] Node::_propagate_ready() (/home/akien/Godot/godot/./scene/main/node.cpp:269)
[18] Node::_propagate_ready() (/home/akien/Godot/godot/./scene/main/node.cpp:258 (discriminator 3))
[19] Node::_set_tree(SceneTree*) (/home/akien/Godot/godot/./scene/main/node.cpp:3181)
[20] SceneTree::initialize() (/home/akien/Godot/godot/./scene/main/scene_tree.cpp:450)
[21] OS_LinuxBSD::run() (/home/akien/Godot/godot/platform/linuxbsd/os_linuxbsd.cpp:958)
[22] /home/akien/Godot/godot/bin/godot.linuxbsd.editor.dev.x86_64(main+0x14b) [0x5a9b1f1] (/home/akien/Godot/godot/platform/linuxbsd/godot_linuxbsd.cpp:85)
[23] /lib64/libc.so.6(+0x2a088) [0x7f83d1600088] (??:0)
[24] /lib64/libc.so.6(__libc_start_main+0x8b) [0x7f83d160014b] (??:0)
[25] /home/akien/Godot/godot/bin/godot.linuxbsd.editor.dev.x86_64(_start+0x25) [0x5a9afe5] (??:?)
-- END OF BACKTRACE --
================================================================

Judging by the backtrace, I suppose this is related to #87387, CC @warriormaster12 @KoBeWi.

[warriormaster12]

@Pshy0 Just pushed a single line change that at least on my end fixed the crash.
#91329