title: DotVvm DataPager not paging
body: <p>I have a GridView which is bound to a GridViewDataSet.  The grid displays correctly along with the Pager. When you try to change the page an error is thrown in the background and the page does not change.</p>
  
  <p><strong>View Code</strong></p>
  
  <pre><code>&lt;bs:GridView DataSource="{value: Skus}" class="table table-striped table-bordered"&gt;
      &lt;Columns&gt;
          &lt;dot:GridViewTextColumn ValueBinding="{value: RecordType}" HeaderText="Category" /&gt;
          &lt;dot:GridViewTextColumn ValueBinding="{value: ContourSku}" HeaderText="Contour SKU" /&gt;
          &lt;dot:GridViewTextColumn ValueBinding="{value: ProductName}" HeaderText="Product Name" /&gt;
          &lt;dot:GridViewTextColumn ValueBinding="{value: CdsCost}" FormatString="c" HeaderText="CDS Cost" /&gt;
          &lt;dot:GridViewTextColumn ValueBinding="{value: ListPrice}" FormatString="c" HeaderText="List Price" /&gt;
          &lt;dot:GridViewTextColumn ValueBinding="{value: ExtendedMrc}" FormatString="c" HeaderText="MRC" /&gt;
  
          &lt;dot:GridViewTemplateColumn HeaderText="Active" AllowSorting="false"&gt;
              &lt;ContentTemplate&gt;
                  &lt;bp:SwitchButton Text="" Checked="{value: IsActive}"&gt;
                  &lt;/bp:SwitchButton&gt;
              &lt;/ContentTemplate&gt;
          &lt;/dot:GridViewTemplateColumn&gt;
      &lt;/Columns&gt;
  &lt;/bs:GridView&gt;
  
  &lt;bs:DataPager DataSet="{value: Skus}" /&gt;
  
  **ViewModel**
  </code></pre>
  
  <pre><code>    [Bind(Direction.ServerToClient)]
      public GridViewDataSet&lt;CloudProductEntity&gt; Skus { get; set; } 
  
      public override Task Init()
      {
          if (!Context.IsPostBack)
          {
              Skus = new GridViewDataSet&lt;CloudProductEntity&gt;
              {
                  PagingOptions = { PageSize = 10 },
                  SortingOptions =
                  {
                      SortDescending = true,
                      SortExpression = nameof(CloudProductEntity.ContourSku)
                  },
              };
              Skus.LoadFromQueryable(CloudProductEntity.Search(Search).AsQueryable());
          }
          return base.Init();
      }
  </code></pre>