I suppose we could create a Stream to wrap this fourth pipe. Considering the `close()` method, which triggers this, is invoked via a periodic loop timer monitoring the process, is there any reliable way to ensure we'd collect an exit code from the stream before close() was called and an `exit` event was emitted?

Perhaps we should skip the event emission if this fourth pipe is available, and rely on a listener for this socket to raise the `exit` event.