Fix RegionUtils.save NPE

BauSystem_Main/src/de/steamwar/bausystem/region/RegionUtils.java

@@ -29,7 +29,9 @@ public class RegionUtils {
     }
 
     static void save(Region region) {
+        if (region.getPrototype() != null) {
             region.regionData.add("prototype", region.getPrototype().getName());
+        }
         region.regionData.add("flagStorage", FlagStorage.toYAPION(region.getFlagStorage()));
         RegionLoader.save();
     }