various console error fixes

src/engine/mobileAI/MobAI.java

@@ -155,7 +155,9 @@ public class MobAI {
     public static void AttackBuilding(Mob mob, Building target) {
 
         try {
-
+            if(target == null){
+                return;
+            }
             if (target.getRank() == -1 || !target.isVulnerable() || BuildingManager.getBuildingFromCache(target.getObjectUUID()) == null) {
                 mob.setCombatTarget(null);
                 return;
@@ -202,6 +204,7 @@ public class MobAI {
             }
 
         } catch (Exception e) {
+            mob.setCombatTarget(null);
             Logger.info(mob.getObjectUUID() + " " + mob.getName() + " Failed At: AttackBuilding" + " " + e.getMessage());
         }
     }