### Godot version

4.1.dev 2e273f0e35800f2bcc7c05db54100caa97928f69

### System information

macOS 13.4

### Issue description

Removing a SpinBox from the node tree using `remove_child` during the line edit text submit signal will crash the engine.

```
handle_crash: Program crashed with signal 11
Engine version: Godot Engine v4.1.dev.custom_build (2e273f0e35800f2bcc7c05db54100caa97928f69)
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[1] 1   libsystem_platform.dylib            0x0000000183b5aa24 _sigtramp + 56
[2] Viewport::gui_get_focus_owner() (in godot.macos.editor.arm64) + 32
[3] SpinBox::_line_edit_focus_exit() (in godot.macos.editor.arm64) + 28
[4] CallQueue::_call_function(Callable const&, Variant const*, int, bool) (in godot.macos.editor.arm64) + 336
[5] CallQueue::flush() (in godot.macos.editor.arm64) + 908
[6] SceneTree::physics_process(double) (in godot.macos.editor.arm64) + 244
[7] Main::iteration() (in godot.macos.editor.arm64) + 528
```

### Steps to reproduce

Open the minimal reproduction project, click on the SpinBox, press enter, and the engine crashes.

### Minimal reproduction project

[SpinBoxTextSubmitCrash.zip](https://github.com/godotengine/godot/files/11631081/SpinBoxTextSubmitCrash.zip)

ERR_READ_THREAD_GUARD_V(nullptr);
	return camera_2d;
}
Transform2D Viewport::get_final_transform() const {
	ERR_READ_THREAD_GUARD_V(Transform2D());
	return stretch_transform * global_canvas_transform;
}
void Viewport::assign_next_enabled_camera_2d(const StringName &p_camera_group) {
	ERR_MAIN_THREAD_GUARD;
	List<Node *> camera_list;
	get_tree()->get_nodes_in_group(p_camera_group, &camera_list);
	Camera2D *new_camera = nullptr;
	for (Node *E : camera_list) {
		Camera2D *cam = Object::cast_to<Camera2D>(E);
		if (!cam) {
			continue; 
		}
		if (cam->is_enabled()) {
			new_camera = cam;
			break;
		}
	}
	_camera_2d_set(new_camera);
	if (!camera_2d) {
		set_canvas_transform(Transform2D());
	}
}
void Viewport::_update_canvas_items(Node *p_node) {