Mild thread-safety issue

[io7m]

If multiple threads attempt to close a collection at the same time, there's a chance that a NoSuchElementException will be raised:

@Override
  public void close()
    throws E
  {
    E e = null;

    while (!this.stack.isEmpty()) {
      final AutoCloseable resource = this.stack.pop();
      try {
        resource.close();
      } catch (final Exception re) {
        if (e == null) {
          e = this.exceptions.get();
        }
        e.addSuppressed(re);
      }
    }

    if (e != null) {
      throw e;
    }
  }

The this.stack.isEmpty() and this.stack.pop() lines result in a time-of-check-time-of-use issue. The stack could have been popped in between the two calls.