Is it normal for DNN to throw an unhandled exception error when having trouble parsing a URL?

These general exceptions are showing up in both the DNN log and the Windows System event log.  

The situation is that, when a misformed URL with at least one parameters after the domain but before the page name, the server logs an error.  

For instance,

www.mydomain.com/something1.aspx  will return a 404 as expected (since I don't have a page called something1)
www.mydomain.com/morestuff/something1.aspx will throw a general exception for an unhandled error.

Message: System.Exception: Unhandled Error: ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Entities.Portals.PortalSettings..ctor(Int32 tabID, PortalAliasInfo objPortalAliasInfo) at DotNetNuke.HttpModules.UrlRewriteModule.OnBeginRequest(Object s, EventArgs e) at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) --- End of inner exception stack trace ---


I would guess that it is in the parsing process for the URL - but I am somewhat new to the DNN world.

Most importantly - is there a setting I can use to redirect users to the home page, or some other useful response when this occurs?

I have tried this on  three different instances of version 5.6.0.   Any help or suggestions are appreciated.

Thanks,
John.