Hi Ken,
Thanks for the bug report. I've just pushed a fix for this to the source code repository.
Just needed to make sure the requestPath actually contains the virtualFolderName:
if (
(useFolderForSiteDetection)
&& (virtualFolderName.Length > 0)
&&(requestPath.Contains(virtualFolderName))
)
{
Now it correctly results in page not found rather than an error.
Best,
Joe