Reactjs 材料界面'；s paperbase premium主题错误：请检查“paperbase”的渲染方法`

我正在使用Material UI的纸质高级主题： 我得到一个错误，说： 错误：元素类型无效：需要字符串（对于内置组件）或类/函数（对于复合组件），但得到：对象。您可能忘记了从定义组件的文件中导出组件，或者您可能混淆了默认导入和命名导入

检查

纸质版

的渲染方法。 有人能帮我纠正这个错误吗

import React from 'react';
import PropTypes from 'prop-types';
import { createMuiTheme, ThemeProvider, withStyles } from '@material-ui/core/styles';
import CssBaseline from '@material-ui/core/CssBaseline';
import Hidden from '@material-ui/core/Hidden';
import Typography from '@material-ui/core/Typography';
import Link from '@material-ui/core/Link';
import Navigator from './Navigator';
import Content from './Content';
import Header from './Header';

function Copyright() {
  return (
    <Typography variant="body2" color="textSecondary" align="center">
      {'Copyright © '}
      <Link color="inherit" href="https://material-ui.com/">
        Your Website
      </Link>{' '}
      {new Date().getFullYear()}
      {'.'}
    </Typography>
  );
}

let theme = createMuiTheme({
  palette: {
    primary: {
      light: '#63ccff',
      main: '#009be5',
      dark: '#006db3',
    },
  },
  typography: {
    h5: {
      fontWeight: 500,
      fontSize: 26,
      letterSpacing: 0.5,
    },
  },
  shape: {
    borderRadius: 8,
  },
  props: {
    MuiTab: {
      disableRipple: true,
    },
  },
  mixins: {
    toolbar: {
      minHeight: 48,
    },
  },
});

theme = {
  ...theme,
  overrides: {
    MuiDrawer: {
      paper: {
        backgroundColor: '#18202c',
      },
    },
    MuiButton: {
      label: {
        textTransform: 'none',
      },
      contained: {
        boxShadow: 'none',
        '&:active': {
          boxShadow: 'none',
        },
      },
    },
    MuiTabs: {
      root: {
        marginLeft: theme.spacing(1),
      },
      indicator: {
        height: 3,
        borderTopLeftRadius: 3,
        borderTopRightRadius: 3,
        backgroundColor: theme.palette.common.white,
      },
    },
    MuiTab: {
      root: {
        textTransform: 'none',
        margin: '0 16px',
        minWidth: 0,
        padding: 0,
        [theme.breakpoints.up('md')]: {
          padding: 0,
          minWidth: 0,
        },
      },
    },
    MuiIconButton: {
      root: {
        padding: theme.spacing(1),
      },
    },
    MuiTooltip: {
      tooltip: {
        borderRadius: 4,
      },
    },
    MuiDivider: {
      root: {
        backgroundColor: '#404854',
      },
    },
    MuiListItemText: {
      primary: {
        fontWeight: theme.typography.fontWeightMedium,
      },
    },
    MuiListItemIcon: {
      root: {
        color: 'inherit',
        marginRight: 0,
        '& svg': {
          fontSize: 20,
        },
      },
    },
    MuiAvatar: {
      root: {
        width: 32,
        height: 32,
      },
    },
  },
};

const drawerWidth = 256;

const styles = {
  root: {
    display: 'flex',
    minHeight: '100vh',
  },
  drawer: {
    [theme.breakpoints.up('sm')]: {
      width: drawerWidth,
      flexShrink: 0,
    },
  },
  app: {
    flex: 1,
    display: 'flex',
    flexDirection: 'column',
  },
  main: {
    flex: 1,
    padding: theme.spacing(6, 4),
    background: '#eaeff1',
  },
  footer: {
    padding: theme.spacing(2),
    background: '#eaeff1',
  },
};

function Paperbase(props) {
  const { classes } = props;
  const [mobileOpen, setMobileOpen] = React.useState(false);

  const handleDrawerToggle = () => {
    setMobileOpen(!mobileOpen);
  };

  return (
    <ThemeProvider theme={theme}>
      <div className={classes.root}>
        <CssBaseline />
        <nav className={classes.drawer}>
          <Hidden smUp implementation="js">
            <Navigator
              PaperProps={{ style: { width: drawerWidth } }}
              variant="temporary"
              open={mobileOpen}
              onClose={handleDrawerToggle}
            />
          </Hidden>
          <Hidden xsDown implementation="css">
            <Navigator PaperProps={{ style: { width: drawerWidth } }} />
          </Hidden>
        </nav>
        <div className={classes.app}>
          <Header onDrawerToggle={handleDrawerToggle} />
          <main className={classes.main}>
            <Content />
          </main>
          <footer className={classes.footer}>
            <Copyright />
          </footer>
        </div>
      </div>
    </ThemeProvider>
  );
}

Paperbase.propTypes = {
  classes: PropTypes.object.isRequired,
};

export default withStyles(styles)(Paperbase);

---

存在两个可能的问题，但如果您设置一个codesandbox以解决所有问题，则会更容易。请显示您的package.json。您是否有错误的stacktrace？存在两个可能的问题，但如果您设置一个codesandbox以解决所有问题，则会更容易。请显示您的package.json。您是否有跟踪错误？

{
  "name": "frontend",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@material-ui/core": "^4.8.3",
    "@material-ui/icons": "^4.5.1",
    "@material-ui/styles": "^4.8.2",
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.3.2",
    "@testing-library/user-event": "^7.1.2",
    "axios": "^0.19.1",
    "classnames": "^2.2.6",
    "jwt-decode": "^2.2.0",
    "react": "^16.12.0",
    "react-dom": "^16.12.0",
    "react-redux": "^7.1.3",
    "react-router-dom": "^5.1.2",
    "react-scripts": "3.3.0",
    "redux": "^4.0.5",
    "redux-thunk": "^2.3.0",
    "styled-components": "^5.0.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "proxy": "http://localhost:5000",
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}