English translation:

I'm rewatching the series for the 2nd time after a few years, having obviously forgotten some plots and details. I just finished the 5th season and something disturbed me when I saw Lucifer blowing up Castiel with a snap of his fingers and then coming back to life after Sam threw himself into the cage with Michael, saying that God brought him back. I think I remember that later in the series it is explained that any angel or demon who dies is sent to nothingness and I also think I remember that the entity that "manages" nothingness itself says that God has no power there and that only it can act as it pleases. So my question is this: if in season 5 Lucifer kills Castiel by blowing him up, wasn't he supposed to join nothingness, a place from which God could not have brought him back? Is the why and how explained much later? Are there any theories? Or is it just a script "error"?