### Godot version

4.1.0

### System information

Windows 10, i711800H, Forward+ Vulkan

### Issue description

When using @export_group("Name") in a BaseClass, then inheriting from that BaseClass in another class and there also using @export_group("Name"), with the same group name, then running the project and re-saving the inherited class the project crashes with 
```
ERROR: FATAL: Index p_index = 3 is out of bounds (size() = 3).
   at: get (./core/templates/cowdata.h:155)
```

sometimes the editor crashes too after a while.

### Steps to reproduce

1. open reproduction project
2. Run the project.
3. Open the "super"script
4. Press CTRL + S to save it.

### Minimal reproduction project

[MRP_.zip](https://github.com/godotengine/godot/files/12137412/MRP_.zip)

} break;
			default:
				break; 
		}
	}
	p_script->static_variables.resize(p_script->static_variables_indices.size());
	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;
			}
		}
		p_script->constants.insert(name, subclass); 
	}
	return OK;
}
Error GDScriptCompiler::_compile_class(GDScript *p_script, const GDScriptParser::ClassNode *p_class, bool p_keep_state) {