Show "404 Page Not Found" page, when non-existing list page set in url

Each In-Portal theme mostly consists of following page types:

• designs - single page layout, that used to create multiple pages
• lists - page, that displays a list of items with pagination and sorting controls
• detail - page, that corresponds to each item, that is being printed on a "list" page

In case, when invalid page number (e.g. too large) is specified in "list" page url (e.g. "?page=5555555"), then 1st page contents in shown instead. This is a fallback, that prevents user from seeing an empty page.

It seems, that in such case it's better to show 404 page instead of showing list's 1st page.