Redux store 中的值总是返回 undefined

尝试将用户输入从表单存储到 redux，但是通过 useSelector 访问的值始终未定义。

切片组件：

import { createSlice } from "@reduxjs/toolkit";

export const userSlice = createSlice({
  name: "userSettings",
  initialState: {
    interval: 15000,
  },
  reducers: {
    updateInterval: (state, action) => {
      state.interval = action.payload
    }
  },
});

export const { updateInterval } = userSlice.actions;
export const userRefreshInterval = (state) => state.userSettings;

export default userSlice.reducer;

输入表单组件：

import React, { useState } from 'react';
import { Button, Form, FormGroup, Label, Input } from 'reactstrap';
import { useSelector, useDispatch } from 'react-redux'
import {userRefreshInterval, updateInterval} from "./store/userSlice.js";

export default function UserSettingsForm() {
  const [refreshInterval, setInterval] = useState("");
  const dispatch = useDispatch();
  const interval = useSelector(userRefreshInterval);

  console.log(interval); // <--- always undefined

  const handleSubmit = (e) => {
    e.preventDefault();
    dispatch(updateInterval(refreshInterval));
  };

  const handleChangeInterval = (text) => {
    setInterval(text);
  };

  return (
    <Form onSubmit={handleSubmit} style={{margin: 10}} inline>
      <FormGroup className="mb-2 mr-sm-2 mb-sm-0">
        <Label for="refreshInterval" className="mr-sm-2">Refresh Interval:</Label>
        <Input type="text" name="refreshInterval" id="refreshInterval" placeholder="interval" onChange={(e) => handleChangeInterval(e.target.value)} />
      </FormGroup>
      <FormGroup className="mb-2 mr-sm-2 mb-sm-0">
        <Label for="roundDecimal" className="mr-sm-2">Round results to decimal: 
        </Label>
        <Input type="text" name="roundDecimal" id="roundDecimal" placeholder="roundDecimal" />
      </FormGroup>
      <Button>Submit</Button>
    </Form>
  );
}

按照要求使用 store.js 更新：

import { configureStore } from '@reduxjs/toolkit'
import userReducer from "./userSlice";

export default configureStore({
  reducer: {
    user: userReducer
  }
})

感觉好像错过了一些简单的事情，请帮助确定问题的原因。