title: Value cannot be null in linq clause
body: <p>I have this method:</p>
  
  <pre><code>protected async Task&lt;List&lt;T&gt;&gt; Get&lt;T&gt;(Expression&lt;Func&lt;T, bool&gt;&gt; select) where T : class, IEntity
  {
      var query = Context.Set&lt;T&gt;();
      query = query.Where(select);
      return await query.ToListAsync&lt;T&gt;();
  }
  </code></pre>
  
  <p>And I call it like this:</p>
  
  <pre><code>var result = await Get&lt;T&gt;(a =&gt; a.Id == myId);
  </code></pre>
  
  <p>But the Get method keeps throwing 'Value cannot be null. Parameter: source'.</p>
  
  <p>What am I missing?</p>
  
  <p>Update 1:<br>
  <code>StackTrace:
  at System.Data.Entity.Utilities.Check.NotNull[T](T value, String parameterName)
  at System.Data.Entity.QueryableExtensions.ToListAsync[TSource](IQueryable'1 source)
  at SoccerPool.MVC5.Models.Config.BaseApiController.&lt;Get&gt;d__49'1.MoveNext() in c:\Projects\SoccerPool\SoccerPool.MVC5\Models\Config\BaseApiController.cs:line 190</code></p>
  
  <p>Update 2:<br>
  <code>Context.Set&lt;T&gt;() is not null. It contains 48 records if I don't perform the linq query. And 'Context' is a property which returns an instance of my DbContext.</code></p>