初学rust，想写个练手的项目，编译报错了，大佬帮忙看看，源码在这里https://files.cnblogs.com/files/xlabs/rust-shop.rar，谢谢。

======================================================================================== error[E0308]: mismatched types --> src\app.rs:185:30 | 185 | Arc::new(Box::new(request_handler)), | ^^^^^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other | = note: expected enum std::result::Result<RustShopResponse<'_>, _> found enum std::result::Result<RustShopResponse<'_>, _>