Since you ask; it has happened, on test servers, that devs have put suns into their cargo holds. It was fun.
It has also happened, on TQ, through misbehaving code that has now been fixed, that the Universe Root was put into a structure that was in a ‘Inventory Graveyard’ (inventory items that are deleted are first moved from the main inventory table into graveyards and then later archived). It was not fun, it caused endless loops in the inventory system under certain conditions since the root item now had a parent.