title: Babel React transform : Property value expected type of string but got null
body: <p>I have an application that is working great client side (transpiled and compiled with Webpack/Babel). </p>
  
  <p>I'm trying to render this app server side with Node, but I'm getting this error : </p>
  
  <pre><code>TypeError: C:/[PROJECT_PATH]/src/_base/common/components/general/AComponent.js: Property value expected type of string but got null
  at Object.validate (C:\[PROJECT_PATH]\node_modules\babel-types\lib\definitions\index.js:153:13)
  at validate (C:\[PROJECT_PATH]\node_modules\babel-types\lib\index.js:269:9)
  at Object.builder (C:\[PROJECT_PATH]\node_modules\babel-types\lib\index.js:222:7)
  at File.&lt;anonymous&gt; (C:\[PROJECT_PATH]\node_modules\babel-core\lib\transformation\file\index.js:329:56)
  at File.addImport (C:\[PROJECT_PATH]\node_modules\babel-core\lib\transformation\file\index.js:336:8)
  at C:\[PROJECT_PATH]\node_modules\babel-plugin-react-transform\lib\index.js:257:46
  at Array.map (native)
  at ReactTransformBuilder.initTransformers (C:\[PROJECT_PATH]\node_modules\babel-plugin-react-transform\lib\index.js:255:40)
  at ReactTransformBuilder.build (C:\[PROJECT_PATH]\node_modules\babel-plugin-react-transform\lib\index.js:164:41)
  at PluginPass.Program (C:\[PROJECT_PATH]\node_modules\babel-plugin-react-transform\lib\index.js:331:17)
  </code></pre>
  
  <p>It happens on any component imported. 
  I know the components themselves work because they do in client mode. </p>
  
  <p>Here is my index.js (same babel config as in client side app) : </p>
  
  <pre><code>require('babel-register')({
    presets:["es2015", "stage-0",'react'],
    highlightCode: false,
    sourceMaps: "both",
    env: {
      development: {
        plugins: [
          'transform-decorators-legacy',
          ["react-transform", {
            transforms: [{
              imports: ['react'],
              locals: ['module']
            }]
          }]
        ]
      }
    }
  });
  
  require('./renderer.js');
  </code></pre>
  
  <p>Here is my renderer.js : </p>
  
  <pre><code>import React, { Component } from 'react'
  
  import Router, {match, RoutingContext } from 'react-router'
  
  // this works :
  import AnyActions from 'path/to/actions/AnyActions'
  
  // this don't
  import AnyComponent from 'path/to/any/component'
  </code></pre>
  
  <p>Everything else is commented out !</p>
  
  <p>I tried to import this simple AComponent : </p>
  
  <pre><code>import React, { Component, PropTypes } from 'react'
  
  export default class AComponent extends Component {
  
    render () { return (&lt;p&gt;Hello&lt;/p&gt;)}
  
  }
  </code></pre>
  
  <p>Same error !</p>
  
  <p>I must miss something obvious ... but I don't see it ! </p>