初学 nodejs 的框架 koa,遇到一个问题解决不了,关于 await next()

const Koa = require("koa");
const multer = require("@koa/multer");
const bodyParser = require("koa-bodyparser");
const Router = require("@koa/router");
const jwt = require("jsonwebtoken");
const crypto = require("crypto");

const app = new Koa();
const router = new Router({ prefix: "/api" });

const secretKey = crypto.randomBytes(32).toString("hex");

const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, "./uploads");
  },
  filename: function (req, file, cb) {
    cb(null, "123" + file.fieldname + "-" + Date.now() + file.originalname);
    // cb(null, file.originalname);
  },
});

const upload = multer({ storage });

const authMiddleware = (ctx, next) => {
  const token = ctx.headers.authorization;
  if (!token) {
    ctx.status = 401;
    return (ctx.body = { code: -1001, message: "未提供令牌" });
  }
  next();
};

router.use(bodyParser());

router.post("/login", (ctx) => {
  const { name, password } = ctx.request.body;
  if (name === "lingo123" && password === "123456") {
    const token = jwt.sign({ name }, secretKey);
    ctx.body = {
      code: 0,
      data: {
        id: 1,
        name,
        token,
      },
    };
  }
});

router.use(authMiddleware);

router.get("/users/:id", (ctx) => {
  const id = ctx.request.params.id;
  ctx.body = id;
});

router.post("/upload", upload.single("photo"), (ctx) => {
  console.log("upload");
  ctx.body = "upload";
});

app.use(router.routes());

app.listen(3000, () => {
  console.log("服务器启动成功~");
});

初学 nodejs,想请教大佬,我想在文件上传这个接口模拟一个 token 校验功能,但是出现了问题,通过 postman 发送上传请求, koa 这边没有问题, postman 接收到的是 404 Not Found,而在将 authMiddleware 修改为异步后就没有问题了?这是为什么?其他的比如 /users/:id 都是可以正常响应的.