got no error log when giving a wrong ip or port

[iiibui]

I think it's better to check if socket error before newChannel since there is no exception cause by socket connect:

nebula/src/common/thrift/ThriftClientManager-inl.h

Lines 75 to 84 in 408d731

	evb->runImmediatelyOrRunInEventBaseThreadAndWait([this, &socket, evb, resolved]() {
	if (enableSSL_) {
	socket = folly::AsyncSSLSocket::newSocket(nebula::createSSLContext(), evb);
	socket->connect(nullptr, resolved.host, resolved.port, FLAGS_conn_timeout_ms);
	} else {
	socket =
	folly::AsyncSocket::newSocket(evb, resolved.host, resolved.port, FLAGS_conn_timeout_ms);
	}
	});
	auto headerClientChannel = apache::thrift::HeaderClientChannel::newChannel(socket);

It's a bit difficult to locate the problem when the --meta_server_addrs configuration is wrong.