System.InvalidOperationException: Sequence contains no matching element
at System.Linq.ThrowHelper.ThrowNoMatchException()
at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)
at AdventureBot.Room.BossBase.MakeDamage(User user, Decimal damage) in /home/ilia/Documents/AdventureBot/AdventureBot/Room/BossBase.cs:line 19
at Content.Items.Bow.OnUse(User user, ItemInfo info) in /home/ilia/Documents/AdventureBot/Content/Items/Bow.cs:line 33
at AdventureBot.Item.ItemInfo.OnUse(User user) in /home/ilia/Documents/AdventureBot/AdventureBot/Item/ItemInfo.cs:line 46
at AdventureBot.Room.RoomBase.UseItem(User user, RecivedMessage message) in /home/ilia/Documents/AdventureBot/AdventureBot/Room/RoomBase.cs:line 234
at AdventureBot.Room.BossBase.OnMessage(User user, RecivedMessage message) in /home/ilia/Documents/AdventureBot/AdventureBot/Room/BossBase.cs:line 86
at AdventureBot.User.MessageManager.OnRecieved(RecivedMessage message) in /home/ilia/Documents/AdventureBot/AdventureBot/User/MessageManager.cs:line 157
at AdventureBot.Messenger.MessengerManager.MessageHandler(RecivedMessage message) in /home/ilia/Documents/AdventureBot/AdventureBot/Messenger/MessengerManager.cs:line 151