### 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)

BIND_ENUM_CONSTANT(SDF_OVERSIZE_MAX);
	BIND_ENUM_CONSTANT(SDF_SCALE_100_PERCENT);
	BIND_ENUM_CONSTANT(SDF_SCALE_50_PERCENT);
	BIND_ENUM_CONSTANT(SDF_SCALE_25_PERCENT);
	BIND_ENUM_CONSTANT(SDF_SCALE_MAX);
	BIND_ENUM_CONSTANT(VRS_DISABLED);
	BIND_ENUM_CONSTANT(VRS_TEXTURE);
	BIND_ENUM_CONSTANT(VRS_XR);
	BIND_ENUM_CONSTANT(VRS_MAX);
}
void Viewport::_validate_property(PropertyInfo &p_property) const {
	if (vrs_mode != VRS_TEXTURE && (p_property.name == "vrs_texture")) {
		p_property.usage = PROPERTY_USAGE_NO_EDITOR;
	}
}
Viewport::Viewport() {
	world_2d = Ref<World2D>(memnew(World2D));
	world_2d->register_viewport(this);
	viewport = RenderingServer::get_singleton()->viewport_create();
	texture_rid = RenderingServer::get_singleton()->viewport_get_texture(viewport);
	default_texture.instantiate();
	default_texture->vp = const_cast<Viewport *>(this);
	viewport_textures.insert(default_texture.ptr());
	default_texture->proxy = RS::get_singleton()->texture_proxy_create(texture_rid);
	canvas_layers.insert(nullptr); // This eases picking code (interpreted as the canvas of the Viewport).
	set_positional_shadow_atlas_size(positional_shadow_atlas_size);
	for (int i = 0; i < 4; i++) {
		positional_shadow_atlas_quadrant_subdiv[i] = SHADOW_ATLAS_QUADRANT_SUBDIV_MAX;
	}
	set_positional_shadow_atlas_quadrant_subdiv(0, SHADOW_ATLAS_QUADRANT_SUBDIV_4);