Forge:1.12.2-2515
exnihilo:1.12-0.1.5

log:
latest.log.txt

i was just composting oak leaves into wooden barrel using hoppers
i will get mod list for you soon
list:
print.txt

What other mods are installed, is this a pack? Are you using default configs? What were you attempting to compost?

I haven't been able to reproduce the game freeze. That looks like a modpack, could you give me a link so I can see if they have made changes to the config. It seems that for some reason the barrel is not getting the recipe items correctly.

try hooking up wooden hoppers into wooden barrels feeding in oak leaves

its a working progress pack im working on but weird things are happening that are hard to track down
skycraft 2.5-1.0.zip

most of the config is default apart from the json bit so i could tweak the drops etc

So using your pack I got the error, but it didn't freeze or crash. Also it doesn't doesn't do it every time. Weird.

let me try doing setup again obviously i took it down from it crashing me

Oh I had interpreted you as meaning vanilla hoppers. Still not able to reliably produce the error using wooden hoppers (haven't seen the error since the first time). Can you replicate it every time? If so can you post a screenshot of the set up.

the setup i was using at the time http://puu.sh/yd8Sf/54774afce8.png

I unfortunately still can not reproduce it. If you find a way to recreate it reliably let us know. It might be some weird interaction with one of the mods you have installed. If no new information or clues turn up in the next few months I will close this issue as can't reproduce.

Until then I am just going to leave this issue open in case anyone else can recreate it and wants to post more information.

yes i agree it might interaction until it happens again no clue what to tell you
will report back if it happens again and i find the culprit