I was fiddling around trying to work out how I was going to prioritise some exporters over others and as soon as I hit save to update the priority on one of them the game closes;

• Crash • https://pastebin.com/8WzhJ0Mp
• Integrated Tunnels • 1.2.1
• MC • 1.10.2
• Forge • 12.18.3.2297

I've had this happen a few times recently, and judging by the concurrent modification exception it's just bad timing with another operation going on in the network?