### 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
_base = nullptr;
				ERR_FAIL_V_MSG(false, "Cyclic inheritance in script class.");
			}
		}
		if (base_cache->_update_exports(r_err, true)) {
			if (r_err && *r_err) {
				return false;
			}
			changed = true;
		}
	}
	if ((changed || p_instance_to_update) && placeholders.size()) { 
		
		HashMap<StringName, Variant> values;
		List<PropertyInfo> propnames;
		_update_exports_values(values, propnames);
		if (changed) {
			for (PlaceHolderScriptInstance *E : placeholders) {
				E->update(propnames, values);
			}
		} else {
			p_instance_to_update->update(propnames, values);
		}
	}
	return changed;
#else
	return false;
#endif
}
void GDScript::update_exports() {