private void verifyTileAt(CrystalNetworkTile te, WorldLocation loc) {
   UUID key = te.getUniqueID();
   WorldLocation prev = verifier.get(key);
   if (prev != null && !prev.equals(loc)) {
     te.getWorld().setBlockToAir(te.getX(), te.getY(), te.getZ());
     throw new InvalidLocationException(te, loc, prev);
   } else verifier.put(key, loc);
 }