Null Exception for tile

[HitomiFlower]

KeyNotFoundException: The given key was not present in the dictionary.
System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) (at <437ba245d8404784b9fbab9b439ac908>:0)
GamePlay.Server.Model.ServerRoundStatus.GetPlayer (System.Int32 playerIndex) (at Assets/Scripts/GamePlay/Server/Model/ServerRoundStatus.cs:70)
GamePlay.Server.Controller.GameState.PlayerDiscardTileState.OnServerStateEnter () (at Assets/Scripts/GamePlay/Server/Controller/GameState/PlayerDiscardTileState.cs:59)
GamePlay.Server.Controller.GameState.ServerState.OnStateEnter () (at Assets/Scripts/GamePlay/Server/Controller/GameState/ServerState.cs:26)
Common.StateMachine.StateMachine.ChangeState (Common.StateMachine.Interfaces.IState newState) (at Assets/Scripts/Common/StateMachine/StateMachine.cs:16)
GamePlay.Server.Controller.ServerBehaviour.DiscardTile (System.Int32 playerIndex, Mahjong.Model.Tile tile, System.Boolean isRichiing, System.Boolean discardLastDraw, System.Int32 bonusTurnTime, System.Boolean turnDoraAfterDiscard) (at Assets/Scripts/GamePlay/Server/Controller/ServerBehaviour.cs:141)
GamePlay.Server.Controller.GameState.PlayerDrawTileState.OnStateUpdate () (at Assets/Scripts/GamePlay/Server/Controller/GameState/PlayerDrawTileState.cs:303)
Common.StateMachine.StateMachine.UpdateState () (at Assets/Scripts/Common/StateMachine/StateMachine.cs:21)
GamePlay.Server.Controller.ServerBehaviour.Update () (at Assets/Scripts/GamePlay/Server/Controller/ServerBehaviour.cs:64)