### 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)

return false;
}
Ref<Image> ViewportTexture::get_image() const {
	if (!vp) {
		if (!vp_pending) {
			ERR_PRINT("Viewport Texture must be set to use it.");
		}
		return Ref<Image>();
	}
	return RS::get_singleton()->texture_2d_get(vp->texture_rid);
}
void ViewportTexture::_setup_local_to_scene(const Node *p_loc_scene) {
	Node *vpn = p_loc_scene->get_node(path);
	ERR_FAIL_COND_MSG(!vpn, "ViewportTexture: Path to node is invalid.");
	vp = Object::cast_to<Viewport>(vpn);
	ERR_FAIL_COND_MSG(!vp, "ViewportTexture: Path to node does not point to a viewport.");
	vp->viewport_textures.insert(this);
	ERR_FAIL_NULL(RenderingServer::get_singleton());
	if (proxy_ph.is_valid()) {
		RS::get_singleton()->texture_proxy_update(proxy, vp->texture_rid);
		RS::get_singleton()->free(proxy_ph);
	} else {
		ERR_FAIL_COND(proxy.is_valid()); 
		proxy = RS::get_singleton()->texture_proxy_create(vp->texture_rid);
	}
	vp_pending = false;
	emit_changed();
}
void ViewportTexture::_bind_methods() {