### 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)

#ifndef _3D_DISABLED
	if (!use_xr) {
#endif
		if (p_allocated) {
			RS::get_singleton()->viewport_set_size(viewport, size.width, size.height);
		} else {
			RS::get_singleton()->viewport_set_size(viewport, 0, 0);
		}
#ifndef _3D_DISABLED
	} 
#endif
	_update_global_transform();
	update_configuration_warnings();
	update_canvas_items();
	for (ViewportTexture *E : viewport_textures) {
		E->emit_changed();
	}
	emit_signal(SNAME("size_changed"));
	Rect2i limit = get_visible_rect();
	for (int i = 0; i < gui.sub_windows.size(); ++i) {
		Window *sw = gui.sub_windows[i].window;
		Rect2i rect = Rect2i(sw->position, sw->size);
		Rect2i new_rect = sw->fit_rect_in_parent(rect, limit);
		if (new_rect != rect) {
			sw->set_position(new_rect.position);
			sw->set_size(new_rect.size);
		}
	}
}
Size2i Viewport::_get_size() const {