我正在构建一个“ReactJS”应用程序并遇到以下错误：

TypeError: theme.spacing is not a function
(anonymous function)
E:/Projects/PortfolioSite/React-Portfolio-Website/react-portfolio-website/src/components/Navbar.js:39
  36 |     avatar:{
  37 |         display: "block",
  38 |         margin: "0.5rem auto",
> 39 |         width: theme.spacing(13),
  40 |         heght: theme.spacing(13)
  41 |     }
  42 | }));

我已经makestyles从"@material-ui/styles". 但它输出上述错误：

为了您的参考，我想添加我使用的完整代码：

import React from 'react';
import {makeStyles} from "@material-ui/styles";

import {
    AppBar,
    Toolbar,
    ListItem,
    ListItemIcon,
    IconButton,
    ListItemText,
    Avatar,
    Divider,
    List,
    Typography,
    Box
} from "@material-ui/core";

import {
    ArrowBack,
    AssignmentInd,
    Home,
    Apps,
    ContactMail

} from "@material-ui/icons";

import avatar from "../Assets/Images/avatar.png";

//CSS styles
const useStyles = makeStyles( theme =>({
    menuSliderContainer:{
        width: 250,
        background: "#511",
        height: "30rem"
    },
    avatar:{
        display: "block",
        margin: "0.5rem auto",
        width: theme.spacing(13),
        heght: theme.spacing(13)
    }
}));

const menuItems = [
    {
        listIcon: <Home/>,
        listText: "Home"
    },
    {
        listIcon: <AssignmentInd/>,
        listText: "Resume"
    },
    {
        listIcon: <Apps/>,
        listText: "Portfolio"
    },    
    {
        listIcon: <ContactMail/>,
        listText: "Contact"
    },    
    {
        listIcon: <Home/>,
        listText: "Home"
    }
]

const Navbar = () => {
    const classes = useStyles()
    return (
        <>
        <Box component="div" className={classes.menuSliderContainer}>
            <Avatar src={avatar} className={classes.avatar} alt="Pawara Siriwardhane"/>
            <Divider/>
            <List>
                {menuItems.map((lstItem,key)=>(
                    <ListItem button key={key}>
                        <ListItemIcon>
                            {lstItem.listIcon}
                        </ListItemIcon>
                        <ListItemText/>
                    </ListItem>
                ))}
            </List>
        </Box>
        <Box component="nav">
            <AppBar position="static" style={{background:"#222"}}>
                <Toolbar>
                <IconButton>
                    <ArrowBack style={{color: "tomato"}}/>
                </IconButton>
                <Typography variant="h5" style={{color:"tan"}}> Portfolio </Typography>
                </Toolbar>
            </AppBar>
        </Box>
        </>
    )
}

export default Navbar

我已经完成了
已经提出的问题：为什么 Material-UI 无法识别 theme.spacing 功能？
& GitHub 对话：[Grid] 使用无单位间距 API #14099
但找不到有效的答案。

如果有人可以解释错误的解决方案，我将非常感激。

先感谢您。