you are right in 18w05a it does not to appening again... in the mean time i've nerver encountert the bug again. and i don't know if it happens again since i've allready updated to 18w05a, without a backup... the only thing i could help you is, to give you the allready updated version, if it helps...
Edit: I'm trying right now to reproduce the bug in a downgraded world, but it does not appear to happening...
no its neither of those... it didn't happend in 1.12.2 and i do not know if it is reproducable, because i dont know exactly what happend. it just stops and does not work again. placing it back makes it stop for one round and stops at the exact place. i do not have an actual screenshot but i can provide a screenshot of the situation.
I just tried downloading the old launcher and booting up an old version of minecraft (1.8.4) and it seems to have done the trick, fingers crossed. Worth a try for anyone having the same issue.
This is what I was advised on the forums; I tried downloading the correct java version and tried allocating minecraft 1, 2, 3, 4, 6, and 8 GBs of memory, and nothing worked. I have contacted mojang support
The output log
That happens in frozen ocean and deep frozen ocean biomes too and sometimes is snow on icebergs missing