Let's do our best to avoid any chance of a WSOD (White Screen Of Death)

I *think* I've worked out all of the possible ways a WSOD might occur so they'll all need fresh eyes and testing please:

- [ ] No `content` dir.
- [ ] A `WP_DEFAULT_THEME` is defined in `content/config.php` but that directory doesn't exist.
- [ ] A `WP_DEFAULT_THEME` is defined in `content/config.php`, that directory exists but it doesn't contain any files.
- [ ] Nothing has been altered since cloning the repo so the `/content/themes/twentyfourteen` directory doesn't exist
- [ ] The `/content/themes/twentyfourteen` has been created but it's empty