### Godot version

v4.0.beta.custom_build [fab9926a9]

### System information

Fedora 37

### Issue description

When creating a new inherited scene, saving the scene (for example with Ctrl+S) defaults to overwriting the scene being inherited, instead of prompting for a location to save to.

### Steps to reproduce

1. Create a new inherited scene
2. Press Ctrl+S

If the scene being inherited is imported (for example from a glTF), an error displays. If the inherited scene is a .tscn or .scn, it gets overridden by an inherited scene that tries to inherit itself, which is impossible and thus corrupt.

### Minimal reproduction project

N/A
StringName base = base_scr->get_instance_base_type();
			if (base != StringName() && EditorNode::get_editor_data().get_custom_types().has(base)) {
				const Vector<EditorData::CustomType> &types = EditorNode::get_editor_data().get_custom_types()[base];
				for (int i = 0; i < types.size(); ++i) {
					if (types[i].script == base_scr && types[i].icon.is_valid()) {
						script_icon_cache[scr] = types[i].icon;
						return types[i].icon;
					}
				}
			}
			base_scr = base_scr->get_base_script();
		}
		
		script_icon_cache[scr] = Ref<Texture>();
	} else if (scr.is_valid() && script_icon_cache.has(scr) && script_icon_cache[scr].is_valid()) {
		return script_icon_cache[scr];
	}
	
	if (p_object->has_meta("_editor_icon")) {
		return p_object->get_meta("_editor_icon");
	}
	if (gui_base->has_theme_icon(p_object->get_class(), SNAME("EditorIcons"))) {
		return gui_base->get_theme_icon(p_object->get_class(), SNAME("EditorIcons"));
	}
	if (p_fallback.length()) {
		return gui_base->get_theme_icon(p_fallback, SNAME("EditorIcons"));
	}
	return nullptr;
}
Ref<Texture2D> EditorNode::get_class_icon(const String &p_class, const String &p_fallback) const {