### 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)

if (gui.key_focus->can_process()) {
				gui.key_focus->_call_gui_input(p_event);
			}
			if (gui.key_event_accepted) {
				set_input_as_handled();
				return;
			}
		}
		Control *from = gui.key_focus ? gui.key_focus : nullptr;
		if (from && p_event->is_pressed()) {
			Control *next = nullptr;
			Ref<InputEventJoypadMotion> joypadmotion_event = p_event;
			if (joypadmotion_event.is_valid()) {
				Input *input = Input::get_singleton();
				if (p_event->is_action_pressed("ui_focus_next") && input->is_action_just_pressed("ui_focus_next")) {
					next = from->find_next_valid_focus();
				}
				if (p_event->is_action_pressed("ui_focus_prev") && input->is_action_just_pressed("ui_focus_prev")) {
					next = from->find_prev_valid_focus();
				}
				if (p_event->is_action_pressed("ui_up") && input->is_action_just_pressed("ui_up")) {
					next = from->_get_focus_neighbor(SIDE_TOP);
				}
				if (p_event->is_action_pressed("ui_left") && input->is_action_just_pressed("ui_left")) {
					next = from->_get_focus_neighbor(SIDE_LEFT);
				}
				if (p_event->is_action_pressed("ui_right") && input->is_action_just_pressed("ui_right")) {
					next = from->_get_focus_neighbor(SIDE_RIGHT);
				}
				if (p_event->is_action_pressed("ui_down") && input->is_action_just_pressed("ui_down")) {