title: Cannot find name 'PropertyKey'
body: <p>I am trying to run Webpack on a project and I am getting multiple errors</p>
  
  <pre><code>node_modules/@types/core-js/index.d.ts
  error TS2304: Cannot find name 'PropertyKey'.
  ...
  node_modules/@types/core-js/index.d.ts
  error TS2339: Property 'for' does not exist on type 'SymbolConstructor'.
  </code></pre>
  
  <p>I should have all my typings installed so I am not sure where these are coming from. I tried copying over a package.json from a project that compiles but it didn't help. What am I missing?</p>
  
  <p>My tsconfig looks like this</p>
  
  <pre><code>{
    "compilerOptions": {
      "target": "es5",
      "emitDecoratorMetadata": true,
      "experimentalDecorators": true,
      "sourceMap": true,
      "noImplicitAny": false,
      "suppressImplicitAnyIndexErrors": true
    },
    "include": [
      "src/**/*"
    ],
    "exclude": [
      "node_modules",
      "**/*.spec.ts"
    ]
  }
  </code></pre>