Fix server assert in case of invalid message from client, just kick t…

…hat client.

src/server.cpp

@@ -1752,7 +1752,13 @@ void Server::ProcessData(u8 *data, u32 datasize, u16 peer_id)
 	else if(command == TOSERVER_CLIENT_READY) {
 		// clients <= protocol version 22 did not send ready message,
 		// they're already initialized
-		assert(peer_proto_ver > 22);
+		if (peer_proto_ver <= 22) {
+			infostream << "Client sent message not expected by a "
+				<< "client using protocol version <= 22,"
+				<< "disconnecing peer_id: " << peer_id << std::endl;
+			m_con.DisconnectPeer(peer_id);
+			return;
+		}
 
 		PlayerSAO* playersao = StageTwoClientInit(peer_id);