Level 7 field cannon error halted game

[rrau]

Playing rise and fall as ghengis khan, i had a level 7 field cannon army that could fire twice per turn. There was nothing for it to do the second fire, but didn't have option to skip turn. It halted game and had to reload from the last autosave 7 turns previous. Save of problem included

Version 1.0.0.220(334528)