Include last sync frame in desync crash log

src/network/network.cpp

@@ -76,6 +76,9 @@ uint32 _sync_seed_2;                  ///< Second part of the seed.
 #endif
 uint64 _sync_state_checksum;          ///< State checksum to compare during sync checks.
 uint32 _sync_frame;                   ///< The frame to perform the sync check.
+Date   _last_sync_date;               ///< The game date of the last successfully received sync frame
+DateFract _last_sync_date_fract;      ///< "
+uint8  _last_sync_tick_skip_counter;  ///< "
 bool _network_first_time;             ///< Whether we have finished joining or not.
 bool _network_udp_server;             ///< Is the UDP server started?
 uint16 _network_udp_broadcast;        ///< Timeout for the UDP broadcasts.
@@ -582,6 +585,10 @@ static void NetworkInitialize(bool close_admins = true)
 	_network_first_time = true;
 
 	_network_reconnect = 0;
+
+	_last_sync_date = 0;
+	_last_sync_date_fract = 0;
+	_last_sync_tick_skip_counter = 0;
 }
 
 /** Non blocking connection create to query servers */

src/network/network_client.cpp

@@ -333,6 +333,9 @@ void ClientNetworkGameSocketHandler::ClientError(NetworkRecvStatus res)
 				my_client->ClientError(NETWORK_RECV_STATUS_DESYNC);
 				return false;
 			}
+			_last_sync_date = _date;
+			_last_sync_date_fract = _date_fract;
+			_last_sync_tick_skip_counter = _tick_skip_counter;
 
 			/* If this is the first time we have a sync-frame, we
 			 *   need to let the server know that we are ready and at the same

src/network/network_internal.h

@@ -118,6 +118,9 @@ extern uint32 _sync_seed_2;
 #endif
 extern uint64 _sync_state_checksum;
 extern uint32 _sync_frame;
+extern Date   _last_sync_date;
+extern DateFract _last_sync_date_fract;
+extern uint8  _last_sync_tick_skip_counter;
 extern bool _network_first_time;
 /* Vars needed for the join-GUI */
 extern NetworkJoinStatus _network_join_status;