Major Description
Paths like this
http://localhost:8080/mycustomapp/faces
should an exception on flash scope and http response 500. Since the prefix is reserved to jsf servlet, it should return 404 not found, because it is not possible to derive a view. Note in portlet case it could be valid, because the viewId can be encoded as a query param.
In this case, a InvalidViewIdException should be thrown and later on restore view phase, we should check if the view was committed, to prevent restore view / rendering code continue and throw other unwanted exceptions.