removing an object in admin that is included in a page block causes a fatal 500 error with message "An exception has been thrown during the rendering of a template ("Could not find 'location' with identifier '70'") in eZDemoBundle:block:content_grid_2cols_2rows.html.twig at line 10."

this error is shown only in dev environment, with prod the error is silent and an blank space shows up in the place where the removed object was taking place.

steps to reproduce:

• setup the environment to "dev"
• open the frontend with a ezDEmo non-legacy siteaccess
• in admin, remove to trash the object /ezdemo_site_admin/Getting-Started/Selected-Features/Create
• clear caches, reload the frontend
• error is displayed