Detecting bluetooth device disconnects/crashes

Hi!
I couldn't find a way to detect if a connection has crashed or disconnected so I tried to implement my own.
In lib/connection.js, I noticed that - if I printed the chunks of the read method - they stop printing as soon as I turn off my bluetooth device; after ~20seconds of apparent frozen behavior, this method continued working, printing chunks of zero length buffers.
Thus, I added the following line
if(chunk.length == 0){ self.emit('error')}
in

(function read(){
      self.isOpen() && self.port.read((err, chunk) => {
        process.nextTick(read);
        if(err) return self.emit('error', err);
        self.emit('data', chunk);
        if(chunk.length == 0){ self.emit('error')}
      });
    })();

This allows me to fetch error events like so:

    connect(address, 1, (err, linkage) => {
      if (err) {
        console.log('connection attempt error');
      } else {
        linkage.on('error', (err) => {
          console.log('disconnected!);
        });
      }
    )}

However my approach assumes I won't be receiving zero length buffers when connected which I realize that might not always be true (or not for all devices);
Also, any thoughts on how to detect the disconnect before the ~20seconds pass?
Thanks!

从 lib/connection.js 开始，检查 read callback，包括零长度缓冲区和读取错误的发出方式。重现 issue 中描述的 Bluetooth 关闭行为，并确定预期的断开连接事件及其发生时机。在不假定有效连接期间不可能出现零长度缓冲区的前提下，定义并覆盖断开连接行为，即视为完成。