Cannot read property 'string' of undefined | React.PropTypes | LayoutPropTypes.js : <p>After deleting and reinstalling my node_modules folder, I'm facing an issue that I don't understand in LayoutPropTypes.js file.</p>

<p>In <code>node_modules/react-native/Libraries/StyleSheet/LayoutPropTypes.js</code>
The following variable is undefined : <code>var ReactPropTypes = require('React').PropTypes;</code></p>

<p>react-native: 0.45.1
react: 16.0.0-alpha.12</p>
