### Godot version

4.0 Beta10

### System information

Windows 10, Vulkan, GTX1060

### Issue description

`PropertyTweener`'s methods' return value are not discarded and effect the unary operator at next line.

In Editor:
![in_editor](https://user-images.githubusercontent.com/61624558/210715100-04bdf283-7954-4be3-94ca-338987b24c5b.png)


In cpp:
![in_cpp](https://user-images.githubusercontent.com/61624558/210715127-519f6d54-fc15-468f-9aca-ba7d387a5a7b.png)


### Steps to reproduce

Just run the Minimal reproduction project.

### Minimal reproduction project

[Bug Report.zip](https://github.com/godotengine/godot/files/10349829/Bug.Report.zip)

prop_info.name = name;
				prop_info.usage = annotation->export_info.usage;
				prop_info.hint_string = annotation->export_info.hint_string;
				p_script->member_info[name] = prop_info;
				p_script->member_indices[name] = minfo;
				p_script->members.insert(name);
			} break;
			default:
				break; 
		}
	}
	parsed_classes.insert(p_script);
	parsing_classes.erase(p_script);
	
	for (int i = 0; i < p_class->members.size(); i++) {
		const GDScriptParser::ClassNode::Member &member = p_class->members[i];
		if (member.type != member.CLASS) {
			continue;
		}
		const GDScriptParser::ClassNode *inner_class = member.m_class;
		StringName name = inner_class->identifier->name;
		Ref<GDScript> &subclass = p_script->subclasses[name];
		GDScript *subclass_ptr = subclass.ptr();
		
		if (!parsing_classes.has(subclass_ptr)) {
			Error err = _populate_class_members(subclass_ptr, inner_class, p_keep_state);
			if (err) {
				return err;
			}
		}