### 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_MAIN_THREAD_GUARD;
	_internal_set_size(p_size);
}
void SubViewport::set_size_force(const Size2i &p_size) {
	ERR_MAIN_THREAD_GUARD;
	// Use only for setting the size from the parent SubViewportContainer with enabled stretch mode.
	// Don't expose function to scripting.
	_internal_set_size(p_size, true);
}
void SubViewport::_internal_set_size(const Size2i &p_size, bool p_force) {
	SubViewportContainer *c = Object::cast_to<SubViewportContainer>(get_parent());
	if (!p_force && c && c->is_stretch_enabled()) {
#ifdef DEBUG_ENABLED
		WARN_PRINT("Can't change the size of a `SubViewport` with a `SubViewportContainer` parent that has `stretch` enabled. Set `SubViewportContainer.stretch` to `false` to allow changing the size manually.");
#endif // DEBUG_ENABLED
		return;
	}
	_set_size(p_size, _get_size_2d_override(), true);
	if (c) {
		c->update_minimum_size();
	}
}
Size2i SubViewport::get_size() const {
	ERR_READ_THREAD_GUARD_V(Size2());
	return _get_size();
}
void SubViewport::set_size_2d_override(const Size2i &p_size) {