Unhandled exception: Null check operator used on a null value

[evstegneych]

SocksProxy.initProxy(proxy: 'SOCKS5 185.105.89.38:27022');
  await HttpClient()
      .getUrl(Uri.parse(
          'https://raw.githubusercontent.com/tayoji-io/socks_proxy/master/README.md'))
      .then((value) {
        return value.close();
      })
      .then((value) {
        return value.transform(utf8.decoder);
      })
      .then((value) {
        return value.fold(
            '', (dynamic previous, element) => previous + element);
      })
      .then((value) => print(value))
      .catchError((e) => print(e));

library code:

error:

fix:

I do not know if it is correct but it works

[i5hi]

I get the same error, but the fix does not work.