Erro: npm run build-dev

Depois de realizar todos os passos até o final da aula 11, obtive um erro de módulo @babel/core não encontrado. Instalei esse módulo e agora tenho o seguinte:

ERROR in ./app-src/app.js
Module build failed (from ./node_modules/babel-loader/lib/index.js):
Error: Plugin/Preset files are not allowed to export objects, only functions.
(...)
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! client@1.0.0 build-dev: `webpack --config webpack.config.js`
npm ERR! Exit status 2
npm ERR! 
npm ERR! Failed at the client@1.0.0 build-dev script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

webpack.config.js:

const path = require('path');

module.exports = {
    mode: 'development',
    entry: './app-src/app.js',
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'dist')
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader'
                }
            }
        ]
    }
}

package.json:

{
  "name": "client",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build-dev": "webpack --config webpack.config.js"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "reflect-metadata": "^0.1.10"
  },
  "devDependencies": {
    "@babel/core": "^7.11.4",
    "@babel/preset-env": "^7.11.0",
    "babel-core": "^6.26.3",
    "babel-loader": "^8.1.0",
    "babel-plugin-transform-decorators-legacy": "^1.3.4",
    "babel-preset-es2017": "^6.24.1",
    "webpack": "^4.44.1",
    "webpack-cli": "^3.3.12"
  }
}

Alguém pode dar uma luz? Obrigada!