title: Chaining multiple include with thenInclude throws System.InvalidOperationException
body: <p>Consider this simplified model:</p>
  
  <pre><code>public class Field 
  {
     public string Name { get; set; }
     public MultilingualString Label { get; set; }
     public MultilingualString Placeholder { get; set; }
  }
  
  public class MultilingualString 
  {
     public string DefaultText { get; set; }
     public IList&lt;Globalization&gt; Globalizations { get; set; }
  }
  
  public class Globalization 
  {
     public string Text { get; set; }
     public Language Language { get; set; }
  }
  
  public class Language
  {
     public string Name { get; set; }
     public string CultureString { get; set; }
  }
  </code></pre>
  
  <p>Using my context, I am trying to get all my fields and include their Label and Placeholder along with the globalizations and language (the whole thing) by using the following command:</p>
  
  <pre><code>var field = context.Fields
     .Include(x =&gt; x.Label.Globalizations)
     .ThenInclude(x =&gt; x.Language)
     .Include(x =&gt; x.Placeholder.Globalizations)
     .ThenInclude(x =&gt; x.Language)
     .ToList();
  </code></pre>
  
  <p>I get the following exception thrown:</p>
  
  <blockquote>
    <p>System.InvalidOperationException
    Invalid attempt to read when no data is present.</p>
  </blockquote>
  
  <p>However, using only the first include/theninclude, I do get the expected results.</p>
  
  <p>What gives? Is this a known bug, or did I misunderstand the Include/ThenInclude syntax?</p>
  
  <p>This is using ef7 beta4 with VS2015 RC</p>