I wasn't around when it happened, but after asking the couple people that were on the server it doesn't sound like they were doing much when it crashed, they were booted from the server, they hadn't gone to disconnect themeslves.

crash report: https://gist.github.com/Corosauce/b9b71b42be689b7763919a9be282d68d

Edit: From discussion with another dev sounds like its due to lazy unreliable design in JDA itself. Damn.

As you say it come from a crash of jda itself. But you can update M2D in 1.1.0 while this version use jda 4 while version 1.0.x use jda 3. Perhaps the rewrite of library has solved this problem.
Ps : if your issue is resolved can you closed it please?