Dragging and dropping node(s) in the Scene dock may cause error message

[Rindbee]

Tested versions

• Reproducible in v4.4.dev3.official [f4af820], ec6a1c0
• Not reproducible in v4.4.dev2.official [97ef3c8]

System information

Godot v4.4.dev2 - Linux Mint 22 (Wilma) - X11 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1050 Ti (nvidia; 535.183.01) - Intel(R) Core(TM) i5-7300HQ CPU @ 2.50GHz (4 Threads)

Issue description

When dragging and dropping nodes in the Scene dock, the following error message may be generated:

ERROR: Index p_column = 0 is out of bounds (cells.size() = 0).
   at: clear_custom_color (scene/gui/tree.cpp:1418)

001.mp4

Bisected to #96124. CC @AeioMuch

002.mp4

In some worse cases (when the node can be added as a sibling node, release the mouse after the color of the node changes), the editor will crash.

================================================================
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.4.dev.custom_build (ec6a1c0e792ac8be44990749800a4654a293b9ee)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] /lib/x86_64-linux-gnu/libc.so.6(+0x45320) [0x790f68c45320] (??:0)
[2] CowData<TreeItem::Cell>::size() const (/opt/godot/godot/./core/templates/cowdata.h:183)
[3] Vector<TreeItem::Cell>::size() const (/opt/godot/godot/./core/templates/vector.h:94)
[4] TreeItem::clear_custom_color(int) (/opt/godot/godot/scene/gui/tree.cpp:1418)
[5] SceneTreeDock::_notification(int) (/opt/godot/godot/editor/scene_tree_dock.cpp:1719)
[6] SceneTreeDock::_notificationv(int, bool) (/opt/godot/godot/editor/scene_tree_dock.h:53)
[7] Object::notification(int, bool) (/opt/godot/godot/core/object/object.cpp:?)
[8] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1242)
[9] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[10] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[11] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[12] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[13] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[14] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[15] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[16] Viewport::_propagate_drag_notification(Node*, int) (/opt/godot/godot/scene/main/viewport.cpp:1243)
[17] Viewport::_perform_drop(Control*) (/opt/godot/godot/scene/main/viewport.cpp:2207)
[18] Viewport::_gui_input_event(Ref<InputEvent>) (/opt/godot/godot/scene/main/viewport.cpp:?)
[19] Viewport::push_input(Ref<InputEvent> const&, bool) (/opt/godot/godot/scene/main/viewport.cpp:3176)
[20] Window::_window_input(Ref<InputEvent> const&) (/opt/godot/godot/scene/main/window.cpp:1651)
[21] void call_with_variant_args_helper<Window, Ref<InputEvent> const&, 0ul>(Window*, void (Window::*)(Ref<InputEvent> const&), Variant const**, Callable::CallError&, IndexSequence<0ul>) (/opt/godot/godot/./core/variant/binder_common.h:304)
[22] void call_with_variant_args<Window, Ref<InputEvent> const&>(Window*, void (Window::*)(Ref<InputEvent> const&), Variant const**, int, Callable::CallError&) (/opt/godot/godot/./core/variant/binder_common.h:419)
[23] CallableCustomMethodPointer<Window, void, Ref<InputEvent> const&>::call(Variant const**, int, Variant&, Callable::CallError&) const (/opt/godot/godot/./core/object/callable_method_pointer.h:111)
[24] Callable::callp(Variant const**, int, Variant&, Callable::CallError&) const (/opt/godot/godot/core/variant/callable.cpp:58)
[25] Variant Callable::call<Ref<InputEvent> >(Ref<InputEvent>) const (/opt/godot/godot/./core/variant/variant.h:905)
[26] DisplayServerX11::_dispatch_input_event(Ref<InputEvent> const&) (/opt/godot/godot/platform/linuxbsd/x11/display_server_x11.cpp:4076)
[27] DisplayServerX11::_dispatch_input_events(Ref<InputEvent> const&) (/opt/godot/godot/platform/linuxbsd/x11/display_server_x11.cpp:4053)
[28] Input::_parse_input_event_impl(Ref<InputEvent> const&, bool) (/opt/godot/godot/core/input/input.cpp:902)
[29] Input::flush_buffered_events() (/opt/godot/godot/core/input/input.cpp:1184)
[30] DisplayServerX11::process_events() (/opt/godot/godot/platform/linuxbsd/x11/display_server_x11.cpp:5213)
[31] OS_LinuxBSD::run() (/opt/godot/godot/platform/linuxbsd/os_linuxbsd.cpp:958)
[32] godot-llvm-dev(main+0x18e) [0x58e9d6b269be] (/opt/godot/godot/platform/linuxbsd/godot_linuxbsd.cpp:86)
[33] /lib/x86_64-linux-gnu/libc.so.6(+0x2a1ca) [0x790f68c2a1ca] (??:0)
[34] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x8b) [0x790f68c2a28b] (??:0)
[35] godot-llvm-dev(_start+0x25) [0x58e9d6b26765] (??:?)
-- END OF BACKTRACE --
================================================================

Steps to reproduce

1. Create a scene and add some nodes in the editor;
2. Select one or some nodes and start dragging;
3. Hover the mouse over a node and wait for the node name under the mouse to change color;
   3.1. If a node box is displayed before the color changes, it means that it can be added as a child node. Move the mouse slightly up or down and release the mouse when the dragged node can be added as a sibling node of the hovered node. An error message will be output.
   3.2. If a line is displayed before the color changes, it can be added as a sibling node. It will crash when you release the mouse.

Minimal reproduction project (MRP)

N/A

[AeioMuch]

Should get fixed by #99700, which supersedes #99122

[KoBeWi]

Can't reproduce it.

nobughere.mp4

[AeioMuch]

I can still reproduce it on master [aa8d9b8]. It seems that when compiling with g++ it does also crash as @Rindbee showed, while when compiling with LLVM/Clang it does only print the error and haven't been able to crash it. Maybe MSVC does something differently that prevent the bug entierly ? Or something else, no idea lol

Regardless there's three options : if #99700 is merged for 4.4, we're good to go.
If not, I have a PR #99122 that does fix it anyway.
Or we simply revert #96124 and merge it back once #99700 is merged.

[AeioMuch]

Fixed by #99700