Prevent showing specific pop-up windows in Revit

Hi all!

I have just created my first Add-in for Revit which will help me to do a simple selection.
I know it sounds weird, but using basic Revit selection it is not possible (as far as I know) to select insulation of the ducts or pipes. Using my add-in, I can simply select pipe with its insulation and filter it out afterwards.

The problem I need to solve is a pop-up window which appears when I run my add-in and hit ESC right away without making any elements selection.
What is the best way to prevent of showing that window? All I want is Revit to terminate my add-in in the background without any pop-up windows as per my attachment below.



Code that I have atm:

namespace RevitAddin
    public class Command : IExternalCommand
        public Result Execute(
          ExternalCommandData commandData,
          ref string message,
          ElementSet elements)
            UIApplication uiapp = commandData.Application;
            UIDocument uidoc = uiapp.ActiveUIDocument;
            Application app = uiapp.Application;
            Document doc = uidoc.Document;

                // Use the rectangle picking tool to identify model elements to select.
                IList<Element> pickedElements = uidoc.Selection.PickElementsByRectangle("Select by rectangle");
                if (pickedElements.Count > 0)
                    // Collect Ids of all picked elements
                    IList<ElementId> idsToSelect = new List<ElementId>(pickedElements.Count);
                    foreach (Element element in pickedElements)

                    // Update the current selection

                return Result.Succeeded;
            catch (Exception e)
                message = e.Message;
                return Result.Failed;