### 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
const GDScript *sptr = this;
	List<PropertyInfo> props;
	while (sptr) {
		Vector<_GDScriptMemberSort> msort;
		for (const KeyValue<StringName, PropertyInfo> &E : sptr->member_info) {
			_GDScriptMemberSort ms;
			ERR_CONTINUE(!sptr->member_indices.has(E.key));
			ms.index = sptr->member_indices[E.key].index;
			ms.name = E.key;
			msort.push_back(ms);
		}
		msort.sort();
		msort.reverse();
		for (int i = 0; i < msort.size(); i++) {
			props.push_front(sptr->member_info[msort[i].name]);
		}
#ifdef TOOLS_ENABLED
		r_list->push_back(sptr->get_class_category());
#endif 
		for (const PropertyInfo &E : props) {
			r_list->push_back(E);
		}
		if (!p_include_base) {
			break;
		}
		props.clear();
		sptr = sptr->_base;
	}
}
void GDScript::get_script_property_list(List<PropertyInfo> *r_list) const {