https://pastebin.com/N2cwaRaa

quark version: r1.4-122
forge version: 14.23.2.2619
java version: 8 update 161

Can confirm the same crash, though for me I was placing fences. I did have multiple stacks of the exact same type of fence (dark oak in this case) in my inventory for it to choose from.

There's already quite a few checks there, I don't know why this is happening. I'll add some thread safety there, but I really doubt that's what's causing it. Please report if it still happens in the next version.