React-dnd: Kesalahan Tidak Tertangkap: Item harus berupa objek

Hai. Saya mencoba menemukan penyebutan bug ini, tetapi sayangnya tidak ada apa pun di sini atau di web.

Saya memulai sebuah proyek dan memiliki pengaturan yang cukup sederhana dan ketika mencoba menyeret elemen, mengalami kesalahan ini:
http://prntscr.com/jpfale

Ini adalah komponen Drag saya:

import React from 'react';
import PropTypes from 'prop-types';
import styled from 'styled-components';
import { DragSource } from 'react-dnd';

const Container = styled.span`
  margin: 10px;
  font-size: 4rem;
  text-transform: uppercase;
  cursor: pointer;
  transition: 0.4s;

  &.is-clicked {
    color: ${({ theme }) => theme.colors.purple};
  }

  &.is-hidden {
    opacity: 0;
  }
`;

const spec = {
  beginDrag(props) {
    console.log('test');
    return {};
  },
};

const WordItem = ({
  children,
  item,
  isHidden,
  handleClick,
  connectDragSource,
}) => {
  return connectDragSource(
    <span>
      <Container
        className={item.clicked ? 'is-clicked' : isHidden}
        onClick={handleClick}
      >
        {children}
      </Container>
    </span>,
  );
};

WordItem.propTypes = {
  children: PropTypes.string.isRequired,
  item: PropTypes.objectOf(PropTypes.any).isRequired,
  isHidden: PropTypes.string.isRequired,
  handleClick: PropTypes.func.isRequired,
};

export default DragSource('word', spec, (connect, monitor) => ({
  connectDragSource: connect.dragSource(),
  isDragging: monitor.isDragging(),
  dropResult: monitor.getDropResult(),
  canDrag: monitor.canDrag(),
}))(WordItem);

Kontainer terhubung dengan konteks:

export default DragDropContext(HTML5Backend)(App);

Saya sudah melakukan satu proyek dengan react-dnd, tetapi ini adalah pertama kalinya saya melihat masalah ini. Ini package.json saya jika masalah ini dapat dikaitkan dengan kompatibilitas perpustakaan:

{
  "name": "",
  "version": "1.0.0",
  "description": "npm i -g prettier",
  "main": "index.js",
  "scripts": {
    "clean": "rimraf dist",
    "dev": "cross-env NODE_ENV=development node devServer.js",
    "build": "npm run clean && cross-env NODE_ENV=production webpack --config=webpack.build.config.js -p && node productionServer.js",
    "flow": "flow"
  },
  "author": "",
  "license": "ISC",
  "browserslist": [
    "last 5 versions",
    "not ie < 11"
  ],
  "prettier": {
    "singleQuote": true,
    "trailingComma": "all"
  },
  "dependencies": {
    "axios": "^0.18.0",
    "babel-plugin-styled-components": "^1.5.1",
    "es6-promise": "^4.2.4",
    "prop-types": "^15.6.1",
    "rc-slider": "^8.6.1",
    "react": "^16.3.2",
    "react-dnd": "^3.0.2",
    "react-dnd-html5-backend": "^3.0.2",
    "react-dom": "^16.3.2",
    "react-motion": "^0.5.2",
    "react-redux": "^5.0.7",
    "react-router-dom": "^4.2.2",
    "redux": "^4.0.0",
    "redux-thunk": "^2.2.0",
    "styled-components": "^3.2.6",
    "svg-inline-loader": "^0.8.0",
    "xml2js": "^0.4.19"
  },
  "devDependencies": {
    "autoprefixer": "^8.3.0",
    "babel-core": "^6.26.0",
    "babel-eslint": "^8.2.3",
    "babel-loader": "^7.1.4",
    "babel-plugin-transform-class-properties": "^6.24.1",
    "babel-plugin-transform-object-rest-spread": "^6.26.0",
    "babel-plugin-transform-runtime": "^6.23.0",
    "babel-preset-env": "^1.6.1",
    "babel-preset-flow": "^6.23.0",
    "babel-preset-react": "^6.24.1",
    "browserslist": "^3.2.4",
    "compression-webpack-plugin": "^1.1.11",
    "cross-env": "^5.1.4",
    "css-loader": "^0.28.11",
    "eslint": "^4.19.1",
    "eslint-config-airbnb": "^16.1.0",
    "eslint-config-prettier": "^2.9.0",
    "eslint-plugin-import": "^2.11.0",
    "eslint-plugin-jsx-a11y": "^6.0.3",
    "eslint-plugin-prettier": "^2.6.0",
    "eslint-plugin-react": "^7.7.0",
    "express": "^4.16.3",
    "extract-text-webpack-plugin": "^4.0.0-beta.0",
    "file-loader": "^1.1.11",
    "flow-bin": "^0.70.0",
    "html-webpack-plugin": "^3.2.0",
    "image-webpack-loader": "^4.2.0",
    "node-sass": "^4.8.3",
    "postcss-loader": "^2.1.4",
    "prettier-eslint": "^8.8.1",
    "react-hot-loader": "^4.0.0",
    "rimraf": "^2.6.2",
    "sass-loader": "^7.0.1",
    "style-loader": "^0.20.3",
    "url-loader": "^1.0.1",
    "webpack": "^4.6.0",
    "webpack-cli": "^2.1.2",
    "webpack-dev-middleware": "^3.1.2",
    "webpack-hot-middleware": "^2.22.1"
  }
}

Tolong bantu menyelesaikan masalah ini.