title: Why does tsc (typescript) give me errors "Cannot find type definition file for xyz"?
body: <p>I read some docs and tried a whole bunch of different things in the tsconfig.json, but no matter what I still get these errors.  Here is the simplest version of my tsconfig.json:</p>
  
  <pre><code>{
    "compilerOptions": {
      "rootDir": "./packages/"
    },
    "exclude": [
      "node_modules",
      "babel.config.js",
      "webpack.config.js",
    ]
  })
  </code></pre>
  
  <p>All my source code is in /packages, and there is only source code there.  The strange thing is the errors I get (below) seem to have nothing to do with my project (the packages contain react-native source code).</p>
  
  <pre><code>error TS2688: Cannot find type definition file for 'anymatch'.
  
  error TS2688: Cannot find type definition file for 'body-parser'.
  
  error TS2688: Cannot find type definition file for 'connect'.
  
  error TS2688: Cannot find type definition file for 'connect-history-api-fallback'.
  
  error TS2688: Cannot find type definition file for 'express'.
  
  error TS2688: Cannot find type definition file for 'express-serve-static-core'.
  
  error TS2688: Cannot find type definition file for 'http-proxy'.
  
  error TS2688: Cannot find type definition file for 'http-proxy-middleware'.
  
  error TS2688: Cannot find type definition file for 'mime'.
  
  error TS2688: Cannot find type definition file for 'range-parser'.
  
  error TS2688: Cannot find type definition file for 'serve-static'.
  
  error TS2688: Cannot find type definition file for 'source-list-map'.
  
  error TS2688: Cannot find type definition file for 'uglify-js'.
  
  error TS2688: Cannot find type definition file for 'webpack'.
  
  error TS2688: Cannot find type definition file for 'webpack-dev-server'.
  
  error TS2688: Cannot find type definition file for 'webpack-sources'.
  </code></pre>
  
  <p>Thanks for any assistance or insight!</p>