### Godot version

4.1.dev

### System information

Win11

### Issue description

I load a non-existing GDScript, but it still returns a valid instance instead of null.
```gdscript
@tool
extends EditorScript

func _run():
	var s = ResourceLoader.load("non_exists.gd", "", ResourceLoader.CACHE_MODE_IGNORE)
	print(s)
	assert(s == null)

```

```
  Attempt to open script 'res://non_exists.gd' resulted in error 'File not found'.
<GDScript#-9223369015982753437>
  res://new_script.gd:7 - Assertion failed.

```

### Steps to reproduce

N/A

### Minimal reproduction project

N/A
if (singleton == nullptr) {
		return;
	}
	MutexLock lock(singleton->mutex);
	if (singleton->cleared) {
		return;
	}
	for (KeyValue<String, HashSet<String>> &E : singleton->packed_scene_dependencies) {
		if (!E.value.has(p_path)) {
			continue;
		}
		E.value.erase(p_path);
	}
	GDScriptCache::clear_unreferenced_packed_scenes();
	if (singleton->parser_map.has(p_path)) {
		singleton->parser_map[p_path]->clear();
		singleton->parser_map.erase(p_path);
	}
	singleton->dependencies.erase(p_path);
	singleton->shallow_gdscript_cache.erase(p_path);
	singleton->full_gdscript_cache.erase(p_path);
}
Ref<GDScriptParserRef> GDScriptCache::get_parser(const String &p_path, GDScriptParserRef::Status p_status, Error &r_error, const String &p_owner) {