void ZlibInStream::removeUnderlying()
{
  ptr = end = start;
  if (!underlying) return;

  while (bytesIn > 0) {
    decompress(true);
    end = start; // throw away any data
  }
  underlying = 0;
}
The software uses, accesses, or otherwise operates on a resource after that resource has been expired, released, or revoked.