It is in example of a known crash: do not report java.util.ConcurrentModificationException. It is going to be fixed in PR-2.0
HOE MTA Crash will not damage your world or anything. It just stops machine processing. They will react to automation(BC Pipes), but will not produce anything. Simply restart your world or server. There will be special op commands to control HOE MTA state(start, stop, reboot, recover) in next versions.
If you want to discuss things(or report bugs) feel free to find me on MCF or in
#ChemLab @ esper.net