tun2socks: fix possible crash when the client side is lost before the SOCKS side manages to connect
tun2socks: fix possible crash when the client side is lost before the SOCKS side manages to connect

SeReRPRo/badvpn,SeReRPRo/badvpn,SeReRPRo/badvpn,SeReRPRo/badvpn,SeReRPRo/badvpn