### 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.dragging) {
			
			Control *drag_preview = _gui_get_drag_preview();
			if (drag_preview) {
				drag_preview->set_position(mpos);
			}
			gui.drag_mouse_over = over;
			gui.drag_mouse_over_pos = Vector2();
			
			
			Viewport *embedder = nullptr;
			Vector2 viewport_pos;
			if (is_embedding_subwindows()) {
				embedder = this;
				viewport_pos = mpos;
			} else {
				
				Window *w = Object::cast_to<Window>(this);
				if (w) {
					if (w->is_embedded()) {
						embedder = w->get_embedder();
						viewport_pos = get_final_transform().xform(mpos) + w->get_position(); 
					}
				}
			}
			Viewport *viewport_under = nullptr;
			if (embedder) {
				
				for (int i = embedder->gui.sub_windows.size() - 1; i >= 0; i--) {
					Window *sw = embedder->gui.sub_windows[i].window;