title: How to use babel/corejs3/webpack correctly for IE11?
body: <p>With my current config (see below), I'm getting this error:</p>
  
  <pre><code>   [object Error]{description: "Argument ob...", message: "Argument ob...", name: "TypeError", number: -2147418113, stack: "TypeError: ...", Symbol()_7.bs7gi3oa3wi: undefined}
  </code></pre>
  
  <p>I tried to dig based on <code>Symbol()_ ... : undefined}</code> but I couldn't find any clear indication.</p>
  
  <p>This is my <code>.babel.config.js</code>:</p>
  
  <pre><code>module.exports = function (api) {
      api.cache(true);
      const presets = [
        [
          '@babel/preset-env',
          {
           // modules: false,
            corejs:"3.6.4",
            useBuiltIns: 'usage',
            targets: {
              browsers: [
                "edge &gt;= 16",
                "safari &gt;= 9",
                "firefox &gt;= 57",
                "ie &gt;= 11",
                "ios &gt;= 9",
                "chrome &gt;= 49"
              ]
            }
          }
        ]
      ];
      const plugins= [
          ["@babel/plugin-proposal-decorators", { decoratorsBeforeExport: true }],
          ["@babel/plugin-proposal-class-properties", { "loose": true }]
      ];
      return {
        presets,
        plugins
      }
    }
  </code></pre>
  
  <p>This is my <code>webpackconfig.js</code></p>
  
  <pre><code>module.exports = {
    module: {
      rules: [
        {
          test: /\.js$/,
         // exclude: /node_modules/,
         exclude : [
          /\bcore-js\b/,
          /\bwebpack\/buildin\b/
        ],
          use: {
            loader: 'babel-loader',
            options:{
              sourceType: "unambiguous"
            }
          },
        },
      ],
    },
    devtool:"cheap-source-map",
    resolve: {
      extensions: ['*', '.js'],
    },
    output: {
      path: path.resolve(__dirname, './dist'),
      filename: 'shim.js',
    }
  };
  </code></pre>
  
  <p>I've also tried many alternatives, this is my current one, with <code>entry:"usage"</code> and not excluding <code>node_modules</code>. </p>
  
  <p>This is from my <code>package.json</code>:</p>
  
  
  
  <pre class="lang-js prettyprint-override"><code> "devDependencies": {
      "@babel/core": "^7.9.0",
      "@babel/plugin-proposal-class-properties": "^7.8.3",
      "@babel/plugin-proposal-decorators": "^7.8.3",
      "@babel/preset-env": "^7.9.5",
      "babel-loader": "^8.1.0",
      "eslint": "^6.8.0",
      "eslint-config-google": "^0.14.0",
      "webpack": "^4.42.1",
      "webpack-cli": "^3.3.11",
      "webpack-dev-server": "^3.10.3",
      "dotenv-webpack": "^1.7.0"
    },
    "dependencies": {
      "core-js": "^3.6.4",
      "ismobilejs": "^1.0.3",
      "localforage": "1.7.3",
      "postmate": "^1.5.2",
      "uuid": "^7.0.3"
    }
  </code></pre>
  
  <p>Error seems to come from the first invocation of the <a href="https://github.com/dollarshaveclub/postmate" rel="noreferrer">Postmate</a> library i.e. <code>new Postmate({...})</code> (I have a <code>console.log</code> just before). Prior to this call, I have one to <code>localforage</code> and the promise complete succesfully.</p>