fix CalculateNetworkFee (#906)

* fix CalculateNetworkFee

* fix in another way

* format

Author: Jim8y

src/RpcServer/RpcServer.Wallet.cs

@@ -130,7 +130,7 @@ protected virtual JToken CalculateNetworkFee(JArray _params)
             JObject account = new();
             var networkfee = Wallets.Helper.CalculateNetworkFee(
                 tx.AsSerializable<Transaction>(), system.StoreView, system.Settings,
-                wallet is not null ? a => wallet.GetAccount(a).Contract.Script : null);
+                wallet is not null ? a => wallet.GetAccount(a).Contract.Script : _ => null);
             account["networkfee"] = networkfee.ToString();
             return account;
         }