### 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_READ_THREAD_GUARD_V(DEFAULT_CANVAS_ITEM_TEXTURE_FILTER_NEAREST);
	return default_canvas_item_texture_filter;
}
void Viewport::set_default_canvas_item_texture_repeat(DefaultCanvasItemTextureRepeat p_repeat) {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_INDEX(p_repeat, DEFAULT_CANVAS_ITEM_TEXTURE_REPEAT_MAX);
	if (default_canvas_item_texture_repeat == p_repeat) {
		return;
	}
	default_canvas_item_texture_repeat = p_repeat;
	switch (default_canvas_item_texture_repeat) {
		case DEFAULT_CANVAS_ITEM_TEXTURE_REPEAT_DISABLED:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_repeat(viewport, RS::CANVAS_ITEM_TEXTURE_REPEAT_DISABLED);
			break;
		case DEFAULT_CANVAS_ITEM_TEXTURE_REPEAT_ENABLED:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_repeat(viewport, RS::CANVAS_ITEM_TEXTURE_REPEAT_ENABLED);
			break;
		case DEFAULT_CANVAS_ITEM_TEXTURE_REPEAT_MIRROR:
			RS::get_singleton()->viewport_set_default_canvas_item_texture_repeat(viewport, RS::CANVAS_ITEM_TEXTURE_REPEAT_MIRROR);
			break;
		default: {
		}
	}
}
Viewport::DefaultCanvasItemTextureRepeat Viewport::get_default_canvas_item_texture_repeat() const {
	ERR_READ_THREAD_GUARD_V(DEFAULT_CANVAS_ITEM_TEXTURE_REPEAT_DISABLED);
	return default_canvas_item_texture_repeat;
}
void Viewport::set_vrs_mode(Viewport::VRSMode p_vrs_mode) {