Herro!
When you hit certain items in SURVIVAL the game closes and crashes.
So far it happens to Brewing Stand, Glowberry Vines. I will add more information if I find more blocks it happens with.
I tried it on a brand-new, unmodded Single Player map, after it had happened on our server, just to verify that it wasn't a mod's fault. It also doesn't happen with previous Forge versions either.
Crash Log: https://pastebin.com/fgN2KLe2
Mostly wanted to report this, so it can hopefully be fixed ASAP?