redux - React / Redux - 错误：动作必须是普通对象。使用自定义中间件进行异步操作

Question

即使我使用的是 redux thunk，我也会收到此错误。Redux 商店也设置正确（我认为）。我正在创建一个 MERN 应用程序，我想向后端发送一个 POST 请求（表单提交）以创建一个新用户。来自服务器的请求和响应都很好（使用 Postman 检查）。我只是找不到问题所在。造成这种情况的动作创建者是：-

    import axios from "axios";
    export function signupUser(newuser) {
        return function (dispatch) {
            axios.post("/auth", newuser).then((res) => {
                // dispatch
                dispatch({
                    type: "ADDNEW_USER",
                    payload: res.data,
                });
            });
        };
    }

The store setup is :-

    import { createStore, applyMiddleware, compose } from "redux";
    import thunk from "redux-thunk";
    import rootReducer from "./reducers";

    const initialState = {};

    // const middleware = [thunk];

    const store = createStore(
        rootReducer,
        initialState,
        compose(
            applyMiddleware(thunk),
            window.__REDUX_DEVTOOLS_EXTENSION__ &&
            window.__REDUX_DEVTOOLS_EXTENSION__()
        )
    );

    export default store;


The Signup.js component is ->
[Signup.js][1]
and the error is -> [here][2]


  [1]: https://paste.ubuntu.com/p/gCX3wQPt9X/
  [2]: https://imgur.com/a/6SDmydw