In Justice League, a number of heroes band together and decide that they need Superman. Only problem is that he's dead (after the events of Batman vs. Superman: Dawn of Justice).

It's clearly been a while since his death, leaving time for Ma Kent to sell the house and Lois Lane to take a leave from work and then write fluff pieces. (Also, the entirety of Suicide Squad happened in the time after Superman died).

And yet Superman's body is perfectly preserved when they open his coffin. Why is it not the least bit decomposed? Does it have something to do with being a Kryptonian? Or is it just handwavey movie logic?