### 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_MAIN_THREAD_GUARD;
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE: {
			_update_viewport_path();
			if (get_parent()) {
				parent = get_parent()->get_viewport();
				RenderingServer::get_singleton()->viewport_set_parent_viewport(viewport, parent->get_viewport_rid());
			} else {
				parent = nullptr;
			}
			current_canvas = find_world_2d()->get_canvas();
			RenderingServer::get_singleton()->viewport_attach_canvas(viewport, current_canvas);
			RenderingServer::get_singleton()->viewport_set_canvas_transform(viewport, current_canvas, canvas_transform);
			RenderingServer::get_singleton()->viewport_set_canvas_cull_mask(viewport, canvas_cull_mask);
			_update_audio_listener_2d();
#ifndef _3D_DISABLED
			RenderingServer::get_singleton()->viewport_set_scenario(viewport, find_world_3d()->get_scenario());
			_update_audio_listener_3d();
#endif 
			add_to_group("_viewports");
			if (get_tree()->is_debugging_collisions_hint()) {
				PhysicsServer2D::get_singleton()->space_set_debug_contacts(find_world_2d()->get_space(), get_tree()->get_collision_debug_contact_count());
				contact_2d_debug = RenderingServer::get_singleton()->canvas_item_create();
				RenderingServer::get_singleton()->canvas_item_set_parent(contact_2d_debug, current_canvas);
#ifndef _3D_DISABLED