I've started using the AI controlled vehicles in the AAI pack for the first time so I think this issue might be relates to that?
The mod Spiderbots (0.3.1) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event spiderbots::on_spider_command_completed (ID 189)
No history for the given key: vehicle-chaingunner-vehicle-chaingunner-gun
stack traceback:
[C]: in function 'get_history'
__spiderbots__/control.lua:558: in function 'create_item_projectile'
__spiderbots__/control.lua:594: in function 'build_ghost'
__spiderbots__/control.lua:1076: in function 'complete_task'
__spiderbots__/control.lua:1104: in function <__spiderbots__/control.lua:1092>