### 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)

int w = icon->get_width();
	if ((w != last_w)) {
		line_edit->set_offset(SIDE_LEFT, 0);
		line_edit->set_offset(SIDE_RIGHT, -w);
		last_w = w;
	}
}
void SpinBox::_update_theme_item_cache() {
	Range::_update_theme_item_cache();
	theme_cache.updown_icon = get_theme_icon(SNAME("updown"));
}
void SpinBox::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_DRAW: {
			_update_text();
			_adjust_width_for_icon(theme_cache.updown_icon);
			RID ci = get_canvas_item();
			Size2i size = get_size();
			if (is_layout_rtl()) {
				theme_cache.updown_icon->draw(ci, Point2i(0, (size.height - theme_cache.updown_icon->get_height()) / 2));
			} else {
				theme_cache.updown_icon->draw(ci, Point2i(size.width - theme_cache.updown_icon->get_width(), (size.height - theme_cache.updown_icon->get_height()) / 2));
			}
		} break;
		case NOTIFICATION_ENTER_TREE: {
			_adjust_width_for_icon(theme_cache.updown_icon);
			_update_text();