### 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)

title_bar.size.y = title_height;
				if (title_bar.size.y > 0 && title_bar.has_point(mb->get_position())) {
					click_on_window = true;
					int close_h_ofs = sw.window->get_theme_constant(SNAME("close_h_offset"));
					int close_v_ofs = sw.window->get_theme_constant(SNAME("close_v_offset"));
					Ref<Texture2D> close_icon = sw.window->get_theme_icon(SNAME("close"));
					Rect2 close_rect;
					close_rect.position = Vector2(r.position.x + r.size.x - close_h_ofs, r.position.y - close_v_ofs);
					close_rect.size = close_icon->get_size();
					if (gui.subwindow_focused != sw.window) {
						
						_sub_window_grab_focus(sw.window);
					}
					if (close_rect.has_point(mb->get_position())) {
						gui.subwindow_drag = SUB_WINDOW_DRAG_CLOSE;
						gui.subwindow_drag_close_inside = true; 
						gui.subwindow_drag_close_rect = close_rect;
					} else {
						gui.subwindow_drag = SUB_WINDOW_DRAG_MOVE;
					}
					gui.subwindow_drag_from = mb->get_position();
					gui.subwindow_drag_pos = sw.window->get_position();
					_sub_window_update(sw.window);
				} else {
					gui.subwindow_resize_mode = _sub_window_get_resize_margin(sw.window, mb->get_position());
					if (gui.subwindow_resize_mode != SUB_WINDOW_RESIZE_DISABLED) {
						if (gui.subwindow_focused != sw.window) {
							
							_sub_window_grab_focus(sw.window);
						}