Trashing all pages can lead to users being trapped with a front page 404

[markel]

If a user sets a page as the front page of their site in Settings > Reading, and then deletes all of the pages from their site, the option to change the front page back to the default is hidden (since no pages exist) and it's not obvious what to change in order to get the selector back.

The selector should either not be hidden when it is configured to use a static page, or the option should be returned to default upon trashing the page that was selected.

Steps to reproduce:

1. Create a page.
2. Set the page to be the front page of the site in Settings > Reading.
3. Trash the page.
4. Navigate back to Settings > Reading. You cannot restore the front page to the recent posts option and visitors to the site are greeted by the 404 page.

If you simply press "Save" on Settings > Reading, it should restore the setting. A pleasant side effect of [14362].

Realistically, like what it does in [15227], if we end up with no pages but we're not currently show_on_front, we should just update the option right away, in addition to spitting out an input=hidden field to update it on save.

Simple patch.

This is less than awesome :-(

Related #15208

(In [16816]) Update show_on_front to posts if there are no pages, just in case. see #14403.

Moving to future. #15208 might be a better long-term solution.

This seems to be fixed in 3.5-beta-1 . I created a page "Home" and went to settings->reading and selected "Home" as the front page. Then deleted the page and went back to settings->reading and it showed "-Select-" for the front page with no errors. When visiting the site it does show the not found page. This is the behavior I expected. Proposing we close this ticket.