My game has a crashed a few times with the following notification- The game crashed whilst unexpected error
Error: java.util.ConcurrentModificationException

https://pastebin.com/z8qFbTA8 is the pastebin of the crash report thingy.

This is happening at random times, nothing specific. Once while walking through a door, once on running between 2 rooms in my base (all chunkloaded if that's relevant) and this current time on while in a worktable inventory and just picking up and ingot to move into my inventory.

I've made no changes to the pack, it's on the latest update, no texture pack or optifine. Running through Twitch launcher thing. I'm not sure if anything else needs adding, any help with this would be gratefully received.

PWLib, which was the source of this crash, has been rolled back to december 2018 version