Add gas refuel sum limit

src/neo/SmartContract/ApplicationEngine.cs

@@ -27,6 +27,7 @@ public partial class ApplicationEngine : ExecutionEngine
         /// The maximum cost that can be spent when a contract is executed in test mode.
         /// </summary>
         public const long TestModeGas = 20_00000000;
+        public const long GasRefueledLimit = 1_00000000;
 
         /// <summary>
         /// Triggered when a contract calls System.Runtime.Notify.
@@ -85,6 +86,7 @@ public partial class ApplicationEngine : ExecutionEngine
         /// GAS spent to execute.
         /// </summary>
         public long GasConsumed { get; private set; } = 0;
+        public long GasRefueledSummary { get; private set; } = 0;
 
         /// <summary>
         /// The remaining GAS that can be spent in order to complete the execution.
@@ -160,6 +162,9 @@ internal void Refuel(long gas)
         {
             checked
             {
+                GasRefueledSummary += gas;
+                if (GasRefueledLimit < GasRefueledSummary)
+                    throw new InvalidOperationException("Exceed gas refuel limit");
                 gas_amount += gas;
             }
         }

src/neo/SmartContract/Native/GasToken.cs

@@ -40,10 +40,10 @@ internal override async ContractTask OnPersist(ApplicationEngine engine)
         [ContractMethod(CpuFee = 1 << 15, RequiredCallFlags = CallFlags.States | CallFlags.AllowNotify)]
         private async ContractTask Refuel(ApplicationEngine engine, UInt160 account, long amount)
         {
-            if (amount < 0) throw new ArgumentOutOfRangeException(nameof(amount));
+            if (amount <= 0) throw new ArgumentOutOfRangeException(nameof(amount));
             if (!engine.CheckWitnessInternal(account)) throw new InvalidOperationException();
-            await Burn(engine, account, amount);
             engine.Refuel(amount);
+            await Burn(engine, account, amount);
         }
     }
 }