Fixed a crash with cashshop errors (#5670)

Fixes #5666

Thanks to @hostragna

src/map/clif.cpp

@@ -16902,7 +16902,11 @@ void clif_cashshop_result( struct map_session_data *sd, t_itemid item_id, uint16
 	struct PACKET_ZC_SE_PC_BUY_CASHITEM_RESULT packet;
 
 	packet.packetType = 0x849;
-	packet.itemId = client_nameid( item_id );
+	if( item_id != 0 ){
+		packet.itemId = client_nameid( item_id );
+	}else{
+		packet.itemId = 0;
+	}
 	packet.result = result;
 	packet.cashPoints = sd->cashPoints;
 	packet.kafraPoints = sd->kafraPoints;