### 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)

p_script->fully_qualified_name = p_class->fqcn;
	p_script->name = p_class->identifier ? p_class->identifier->name : "";
	HashMap<StringName, Ref<GDScript>> old_subclasses;
	if (p_keep_state) {
		old_subclasses = p_script->subclasses;
	}
	p_script->subclasses.clear();
	for (int i = 0; i < p_class->members.size(); i++) {
		if (p_class->members[i].type != GDScriptParser::ClassNode::Member::CLASS) {
			continue;
		}
		const GDScriptParser::ClassNode *inner_class = p_class->members[i].m_class;
		StringName name = inner_class->identifier->name;
		Ref<GDScript> subclass;
		if (old_subclasses.has(name)) {
			subclass = old_subclasses[name];
		} else {
			subclass = GDScriptLanguage::get_singleton()->get_orphan_subclass(inner_class->fqcn);
		}
		if (subclass.is_null()) {
			subclass.instantiate();
		}
		subclass->_owner = p_script;
		subclass->path = p_script->path;
		p_script->subclasses.insert(name, subclass);
		make_scripts(subclass.ptr(), inner_class, p_keep_state);
	}
}
Error GDScriptCompiler::compile(const GDScriptParser *p_parser, GDScript *p_script, bool p_keep_state) {