### 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
for (const KeyValue<StringName, Variant> &E : member_default_values_cache) {
		values[E.key] = E.value;
	}
	for (const PropertyInfo &E : members_cache) {
		propnames.push_back(E);
	}
	if (base_cache.is_valid()) {
		base_cache->_update_exports_values(values, propnames);
	}
}
void GDScript::_add_doc(const DocData::ClassDoc &p_inner_class) {
	if (_owner) { 
		_owner->_add_doc(p_inner_class);
	} else { 
		for (int i = 0; i < docs.size(); i++) {
			if (docs[i].name == p_inner_class.name) {
				docs.remove_at(i);
				break;
			}
		}
		docs.append(p_inner_class);
	}
}
void GDScript::_clear_doc() {
	docs.clear();
	doc = DocData::ClassDoc();
}
#endif
bool GDScript::_update_exports(bool *r_err, bool p_recursive_call, PlaceHolderScriptInstance *p_instance_to_update) {