System.ArgumentNullException: Value cannot be null.
Parameter name: input
   at System.Text.RegularExpressions.Regex.Matches(String input)
   at System.Text.RegularExpressions.Regex.Matches(String input, String pattern, RegexOptions options)
   at Umbraco.Web.Templates.TemplateUtilities.ParseInternalLinks(String text)
   at ASP._Page_Views_Partials_Grid_Editors_DocTypeGridEditor_widgetText_cshtml.Execute() in C:\SERVICES\WEBSITES\OudeMuziek2017_Website\Website\wwwroot_1144\Views\Partials\Grid\Editors\DocTypeGridEditor\widgetText.cshtml:line 35
   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 Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at Our.Umbraco.DocTypeGridEditor.Web.Extensions.HtmlHelperExtensions.RenderDocTypeGridEditorItem(HtmlHelper helper, IPublishedContent content, String editorAlias, String viewPath, String previewViewPath)
   at ASP._Page_app_plugins_doctypegrideditor_render_doctypegrideditor_cshtml.Execute() in C:\SERVICES\WEBSITES\OudeMuziek2017_Website\Website\wwwroot_1144\app_plugins\doctypegrideditor\render\doctypegrideditor.cshtml:line 28
   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 Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at ASP._Page_Views_Partials_grid_editors_base_cshtml.Execute() in C:\SERVICES\WEBSITES\OudeMuziek2017_Website\Website\wwwroot_1144\Views\Partials\grid\editors\base.cshtml:line 19