title: EF core NullReferenceException accessing related entity
body: <p>How do you update a subtable value with Lambda EF core.</p>
  
  <pre><code>var UpdatePercentage = _context.TaskOverview.Single(c =&gt; c.Id == 100);
  UpdatePercentage.Completedpercentage = 30;
  UpdatePercentage.TaskSubInfo.Content1 = "Some value";
  
  await _context.SaveChangesAsync();
  </code></pre>
  
  <p>I get NullReferenceException error</p>
  
  <pre><code>NullReferenceException: Object reference not set to an instance of an object.
  </code></pre>