System.NullReferenceException: Object reference not set to an instance of an object.
   at Umbraco.Core.Cache.HttpRequestCacheProvider.GetCacheItem(String cacheKey, Func`1 getCacheItem)
   at Our.Umbraco.DocTypeGridEditor.Helpers.DocTypeGridEditorHelper.ConvertValueToContent(String id, String contentTypeAlias, String dataJson)
   at ASP._Page_app_plugins_doctypegrideditor_render_DocTypeGridEditor_cshtml.Execute() in C:\home\site\wwwroot\app_plugins\doctypegrideditor\render\DocTypeGridEditor.cshtml:line 26
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance)
   at System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer)
   at Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model)
   at ASP._Page_Views_Partials_grid_editors_Base_cshtml.Execute() in C:\home\site\wwwroot\Views\Partials\grid\editors\Base.cshtml:line 20