When the scripts are loaded through a script manager with enabled CDN and RadScriptManager.CombinedResource="Enabled", JS error will be thrown then the filtering button of the Grid is clicked.

Code to reproduce the problem:
        <telerik:RadScriptManager ID="RadScriptManager1" runat="server">
            <CdnSettings TelerikCdn="Enabled" CombinedResource="Enabled" />
        </telerik:RadScriptManager>

        <telerik:RadGrid ID="UserDetailsGrid" runat="server" AllowFilteringByColumn="true" OnNeedDataSource="UserDetailsGrid_NeedDataSource"
            EnableHeaderContextMenu="true" EnableHeaderContextFilterMenu="true">
        </telerik:RadGrid>

C#:
        protected void UserDetailsGrid_NeedDataSource(object sender, Telerik.Web.UI.GridNeedDataSourceEventArgs e)
        {
            var list = new[] {
                    new { FirstName = "F1", LastName ="L1"},
                    new { FirstName = "F2", LastName ="L2"},
                    new { FirstName = "F3", LastName ="L3"},
                    new { FirstName = "F4", LastName ="L4"}
                    }.ToList();
            UserDetailsGrid.DataSource = list;
        }