Space for widget which not exist

This Widget is normally the google searchbar.
If it is missing - the chances are high that you've removed the Google application from your phone. The missing widget can't be found and the empty box with the error message appears as we can see in your screenshot.

Luckily you are running cyanogenmod which lets you hide this widget from the recent apps screen. To do this go to:

Settings > Display & LED > Searchbar in Recent Apps

Disable the option and the widget should be gone.

I'll try to add screenshots when I get home this evening.