如何修复Rust Rocket框架中POST请求的解析错误

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use] extern crate rocket;

use rocket::serde::{Serialize, json::Json};
use serde::Deserialize;

#[derive(Serialize, Deserialize, Debug)]
struct User {
    name: String,
    email: String,
}

#[post("/user", data = "<user>")]
fn create_user(user: Json<User>) -> Result<String, String> {
    if user.name.is_empty() || user.email.is_empty() {
        Err("Name and email are required".to_string())
    } else {
        Ok(format!("User created: {:?}", user))
    }
}

#[rocket::main]
async fn main() {
    rocket::ignite()
        .mount("/", routes![create_user])
        .launch()
        .await
        .expect("Failed to launch rocket");
}

#[derive(Serialize, Deserialize, Debug)]
struct User {
    name: String,
    email: Option<String>,
}