This has been reported, however, not with a full report and logs.
GC v.1.12.2, Forge v.2705

crash-2018-05-31_20.06.07-server.txt
latest.log
debug.log

You are using outdated version of GC. We will publish a new one at curseforge. Actually it is already available only at discord on the dev channel.

Outdated by four days? 😂 You guys work fast.

Awesome, thank you. Just grabbed it and it's working great, so far!