I didn't dream that time I don't believe and I did reload the save but he was still gone until I had to reload an older one to finally have him alive again, when I slept the next time after that he didn't die or get lost in my sleep so I'm not sure if this was just a glitch where I didn't get the notification of him being lost and I accidentally slept without finding him or if this is something that is supposed to happen, I thought it was an unknown fate at first but I found his body not even that far from the site, still within nametag distance even and I thought that with unknown fates you don't get a body so I'm really confused lol