fix getcontractstate (#3282)

src/Plugins/RpcServer/RpcServer.Blockchain.cs

@@ -119,15 +119,13 @@ protected virtual JToken GetContractState(JArray _params)
         {
             if (int.TryParse(_params[0].AsString(), out int contractId))
             {
-                var contracts = NativeContract.ContractManagement.GetContractById(system.StoreView, contractId);
-                return contracts?.ToJson().NotNull_Or(RpcError.UnknownContract);
-            }
-            else
-            {
-                UInt160 script_hash = ToScriptHash(_params[0].AsString());
-                ContractState contract = NativeContract.ContractManagement.GetContract(system.StoreView, script_hash);
-                return contract?.ToJson().NotNull_Or(RpcError.UnknownContract);
+                var contractState = NativeContract.ContractManagement.GetContractById(system.StoreView, contractId);
+                return contractState.NotNull_Or(RpcError.UnknownContract).ToJson();
             }
+
+            var scriptHash = ToScriptHash(_params[0].AsString());
+            var contract = NativeContract.ContractManagement.GetContract(system.StoreView, scriptHash);
+            return contract.NotNull_Or(RpcError.UnknownContract).ToJson();
         }
 
         private static UInt160 ToScriptHash(string keyword)

tests/Neo.Plugins.RpcServer.Tests/UT_Result.cs

@@ -0,0 +1,26 @@
+// Copyright (C) 2015-2024 The Neo Project.
+//
+// UT_Result.cs file belongs to the neo project and is free
+// software distributed under the MIT software license, see the
+// accompanying file LICENSE in the main directory of the
+// repository or http://www.opensource.org/licenses/mit-license.php
+// for more details.
+//
+// Redistribution and use in source and binary forms with or without
+// modifications are permitted.
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Neo.SmartContract;
+
+namespace Neo.Plugins.RpcServer.Tests;
+
+[TestClass]
+public class UT_Result
+{
+    [TestMethod]
+    public void TestNotNull_Or()
+    {
+        ContractState? contracts = null;
+        Assert.ThrowsException<RpcException>(() => contracts.NotNull_Or(RpcError.UnknownContract).ToJson());
+    }
+}