Fix TypeError and add proper redirection when deleting via the details panel

Closes #692 (closed)

The deletion button from the DetailsPanel did not handle well the deletion of the main element itself (it was only intended to delete a child element like a line on a page). It tried to just re-select the main element, even when this is the element that got deleted, causing various TypeErrors around the page. This uses a similar method as the redirection code from HeaderActions.