Tree's set_selected() does not check if TreeItem belongs to the Tree

[KoBeWi]

Godot version

4.2 beta6

System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

Issue description

Tree allows selecting TreeItem from another Tree, resulting in a crash:

CrashHandlerException: Program crashed
Engine version: Godot Engine v4.2.beta.custom_build (59457685c18e2d729eea50c751c11f049a7186f0)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[0] CowData<TreeItem::Cell>::_get_size (C:\godot_source\core\templates\cowdata.h:81)
[1] CowData<TreeItem::Cell>::size (C:\godot_source\core\templates\cowdata.h:134)
[2] VectorWriteProxy<TreeItem::Cell>::operator[] (C:\godot_source\core\templates\vector.h:52)
[3] Tree::select_single_item (C:\godot_source\scene\gui\tree.cpp:2574)
[4] Tree::set_selected (C:\godot_source\scene\gui\tree.cpp:4548)
[5] call_with_variant_args_helper<Tree,TreeItem *,int,0,1> (C:\godot_source\core\variant\binder_common.h:308)
[6] call_with_variant_args_dv<Tree,TreeItem *,int> (C:\godot_source\core\variant\binder_common.h:451)
[7] MethodBindT<Tree,TreeItem *,int>::call (C:\godot_source\core\object\method_bind.h:337)
[8] Object::callp (C:\godot_source\core\object\object.cpp:775)
[9] Variant::callp (C:\godot_source\core\variant\variant_call.cpp:1168)
[10] GDScriptFunction::call (C:\godot_source\modules\gdscript\gdscript_vm.cpp:1705)
[11] GDScriptInstance::callp (C:\godot_source\modules\gdscript\gdscript.cpp:1975)
[12] Node::_gdvirtual__ready_call<0> (C:\godot_source\scene\main\node.h:322)
[13] Node::_notification (C:\godot_source\scene\main\node.cpp:188)
[14] Node::_notificationv (C:\godot_source\scene\main\node.h:49)
[15] Object::notification (C:\godot_source\core\object\object.cpp:840)
[16] Node::_propagate_ready (C:\godot_source\scene\main\node.cpp:232)
[17] Node::_propagate_ready (C:\godot_source\scene\main\node.cpp:223)
[18] Node::_propagate_ready (C:\godot_source\scene\main\node.cpp:223)
[19] Node::_set_tree (C:\godot_source\scene\main\node.cpp:2941)
[20] SceneTree::initialize (C:\godot_source\scene\main\scene_tree.cpp:450)
[21] OS_Windows::run (C:\godot_source\platform\windows\os_windows.cpp:1472)
[22] widechar_main (C:\godot_source\platform\windows\godot_windows.cpp:182)
[23] _main (C:\godot_source\platform\windows\godot_windows.cpp:204)
[24] main (C:\godot_source\platform\windows\godot_windows.cpp:218)
[25] WinMain (C:\godot_source\platform\windows\godot_windows.cpp:232)
[26] __scrt_common_main_seh (D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288)
[27] <couldn't map PC to fn name>
-- END OF BACKTRACE --

Steps to reproduce

1. Make a scene with 2 Tree nodes
2. Run this code

func _ready() -> void:
	var item = $Tree.create_item()
	$Tree2.set_selected(item, 0)

Minimal reproduction project

N/A

[jsjtxietian]

The cause of crash is that get_root returns null, if the tree has some tree items, it won't crash but just sliently fail to set selected, nothing worse will happen. But it should check the tree item belongs to tree.