### 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)

ERR_FAIL_COND(p_event.is_null());
	Ref<InputEventMouseButton> mb = p_event;
	if (mb.is_valid()) {
		gui.key_event_accepted = false;
		Point2 mpos = mb->get_position();
		if (mb->is_pressed()) {
			if (!gui.mouse_focus_mask.is_empty()) {
				
				gui.mouse_focus_mask.set_flag(mouse_button_to_mask(mb->get_button_index()));
			} else {
				gui.mouse_focus = gui_find_control(mpos);
				gui.last_mouse_focus = gui.mouse_focus;
				if (!gui.mouse_focus) {
					gui.mouse_focus_mask.clear();
					return;
				}
				gui.mouse_focus_mask.clear();
				gui.mouse_focus_mask.set_flag(mouse_button_to_mask(mb->get_button_index()));
				if (mb->get_button_index() == MouseButton::LEFT) {
					gui.drag_accum = Vector2();
					gui.drag_attempted = false;
				}
			}
			mb = mb->xformed_by(Transform2D()); 
			Point2 pos = gui.mouse_focus->get_global_transform_with_canvas().affine_inverse().xform(mpos);