title: React Native : Cannot read property 'Document Dir' of undefined when importing react-native-fetch-blob
body: <p>I was trying to use react-native-fetch-blob in my project, but whenever I put an</p>
  
  <p><code>import RNFetchBlob from 'react-native-fetch-blob'</code> </p>
  
  <p>and I get an error on the emulator as</p>
  
  <p><code>Cannot read property 'Document Dir' of undefined</code></p>
  
  <p>I have installed it using </p>
  
  <pre><code>npm i --save react-native-fetch-blob
  </code></pre>
  
  <p>and linked it using</p>
  
  <pre><code>react-native link
  </code></pre>
  
  <p>Error :</p>
  
  <blockquote>
    <p>Cannot read property 'DocumentDir' of undefined 
        fs.js:24:31 loadModuleImplementation
        require.js:214:4 guardedLoadModule
        require.js:148:11
    _require
        require.js:132:2 
        index.js:21 loadModuleImplementation
        require.js:214:4 guardedLoadModule
        require.js:148:11
    _require
        require.js:132:2 
        App.js:6 loadModuleImplementation
        require.js:214:4</p>
  </blockquote>