CI: CategoryViewer - DrillDown view error when no category is set

[coretoco]

Problem:
Category Viewer DrillDown View does not work without category set

Discussion Thread:
https://hotcakes.org/Forums/g/posts/t/87/Creating-ProductTypeProperty-Filter-on-Category-Viewer

Steps to reproduce the problem
Drop CategoryViewer on a page
In Hotcakes Category Viewer Settings configure the following
--> Select a category: set to "(None selected)
--> Select a view: set to "DrillDown"
Save

Stack Trace:
Error: Produkte ist zur Zeit nicht verfügbar. DotNetNuke.Services.Exceptions.ModuleLoadException: Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerAsyncWrapper'. ---> System.Web.HttpException: Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerAsyncWrapper'. ---> System.NullReferenceException: Object reference not set to an instance of an object. at Hotcakes.Modules.Core.Controllers.CategoryController.BuildDrillDownQuery(CategoryFilterViewModel filter) at Hotcakes.Modules.Core.Controllers.CategoryController.BuildDrillDownModel(CategoryFilterViewModel filter, CategoryModuleSettings sett, Int32 pageNumber, Int32 pageSize) at Hotcakes.Modules.Core.Controllers.CategoryController.Index(String slug, Int32 productPageSize, String preContentColumnId, String postContentColumnId) at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult2.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.b__3f() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass48.b__41() at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass48.b__41() at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.<>c__DisplayClass2b.b__1c() at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass21.b__1e(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) at System.Web.Mvc.Controller.b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) at System.Web.Mvc.MvcHandler.b__5(IAsyncResult asyncResult, ProcessRequestState innerState) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.<>c__DisplayClass4.<Wrap>b__3() at System.Web.Mvc.HttpHandlerUtil.ServerExecuteHttpHandlerWrapper.Wrap[TResult](Func1 func) at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) --- End of inner exception stack trace --- at System.Web.HttpServerUtility.ExecuteInternal(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage, VirtualPath path, VirtualPath filePath, String physPath, Exception error, String queryStringOverride) at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm, Boolean setPreviousPage) at System.Web.HttpServerUtility.Execute(IHttpHandler handler, TextWriter writer, Boolean preserveForm) at System.Web.Mvc.Html.ChildActionExtensions.ActionHelper(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues, TextWriter textWriter) at System.Web.Mvc.Html.ChildActionExtensions.Action(HtmlHelper htmlHelper, String actionName, String controllerName, RouteValueDictionary routeValues) at Hotcakes.Commerce.Dnn.Mvc.MvcRenderingEngine.Render(String controllerName, String actionName, String viewName, Object routeValues) at Hotcakes.Modules.CategoryViewer.CategoryViewerView.RenderView() at Hotcakes.Commerce.Dnn.Web.HotcakesModuleBase.OnLoad(EventArgs e) --- End of inner exception stack trace ---`

[WillStrohl]

Passed QA