disappearance of objects

Hello, as are mojang developers, I have come to report an error that occurred to me a few minutes ago.

I was playing minecraft in my survival world

I got into a Mineshaft and started exploring, I found a cave spider spawn so I started killing them all because I wanted to put a torch in their spawn to make me a spider farm, but they killed me

After a few seconds I returned to the point where I died and my things were and I looked back and when I saw my things they had disappeared, search and search but nothing, this has already happened to me twice and I am tired of this, please fix this problem