### 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)

} break;
		case NOTIFICATION_EXIT_TREE: {
			_release_mouse();
		} break;
		case NOTIFICATION_TRANSLATION_CHANGED: {
			queue_redraw();
		} break;
		case NOTIFICATION_THEME_CHANGED: {
			call_deferred(SNAME("update_minimum_size"));
			get_line_edit()->call_deferred(SNAME("update_minimum_size"));
		} break;
		case NOTIFICATION_LAYOUT_DIRECTION_CHANGED: {
			queue_redraw();
		} break;
	}
}
void SpinBox::set_horizontal_alignment(HorizontalAlignment p_alignment) {
	line_edit->set_horizontal_alignment(p_alignment);
}
HorizontalAlignment SpinBox::get_horizontal_alignment() const {
	return line_edit->get_horizontal_alignment();
}
void SpinBox::set_suffix(const String &p_suffix) {
	if (suffix == p_suffix) {
		return;
	}
	suffix = p_suffix;
	_update_text();
}
String SpinBox::get_suffix() const {