Error trap when deranking during maintenance.

src/engine/gameManager/MaintenanceManager.java

@@ -59,8 +59,12 @@ public enum MaintenanceManager {
         // Derak or destroy buildings that did not
         // have funds available.
 
-        for (Building building : derankList)
+        try {
-            building.destroyOrDerank(null);
+            for (Building building : derankList)
+                building.destroyOrDerank(null);
+        } catch (Exception e) {
+            Logger.error(e);
+        }
 
         Logger.info("Structures: " + buildingList.size() + " Maint: " + maintList.size() + " Derank: " + derankList.size());
     }