Terra Invicta build 1.0.53a - Crash fix

This fixes a crash that can happen if a factionless army assaults an alien facility on Earth. This can occur if an army loses its faction in the middle of an assault. This mirrors a fix in 1.0.54 (on our Beta branch with many other updates), but people are hitting this particular crash often enough in DLC scenarios we're pushing out a fix to the default build.