Fix IndexOutOfRangeException on missing or mismatched receipts in BlockValidator

src/Nethermind/Nethermind.Blockchain.Test/Validators/BlockValidatorTests.cs

@@ -202,6 +202,44 @@ public void ValidateProcessedBlock_StateRootIsWrong_ErrorIsSet()
         Assert.That(error, Does.StartWith("InvalidStateRoot"));
     }
 
+    [Test]
+    public void ValidateProcessedBlock_ReceiptCountMismatch_DoesNotThrow()
+    {
+        TxValidator txValidator = new(TestBlockchainIds.ChainId);
+        ISpecProvider specProvider = Substitute.For<ISpecProvider>();
+        BlockValidator sut = new(txValidator, Always.Valid, Always.Valid, specProvider, LimboLogs.Instance);
+        Block suggestedBlock = Build.A.Block.TestObject;
+        Block processedBlock = Build.A.Block
+            .WithStateRoot(Keccak.Zero)
+            .WithTransactions(2, specProvider)
+            .TestObject;
+
+        Assert.DoesNotThrow(() => sut.ValidateProcessedBlock(
+            processedBlock,
+            [],
+            suggestedBlock));
+    }
+
+    [Test]
+    public void ValidateProcessedBlock_ReceiptCountMismatch_ReturnsFalse()
+    {
+        TxValidator txValidator = new(TestBlockchainIds.ChainId);
+        ISpecProvider specProvider = Substitute.For<ISpecProvider>();
+        BlockValidator sut = new(txValidator, Always.Valid, Always.Valid, specProvider, LimboLogs.Instance);
+        Block suggestedBlock = Build.A.Block.TestObject;
+        Block processedBlock = Build.A.Block
+            .WithStateRoot(Keccak.Zero)
+            .WithTransactions(3, specProvider)
+            .TestObject;
+
+        bool result = sut.ValidateProcessedBlock(
+            processedBlock,
+            [Build.A.Receipt.TestObject],
+            suggestedBlock);
+
+        Assert.That(result, Is.False);
+    }
+
     private static IEnumerable<TestCaseData> BadSuggestedBlocks()
     {
         BlockHeader parent = Build.A.BlockHeader.TestObject;

src/Nethermind/Nethermind.Consensus/Validators/BlockValidator.cs

@@ -212,12 +212,20 @@ public bool ValidateProcessedBlock(Block processedBlock, TxReceipt[] receipts, B
             error ??= BlockErrorMessages.InvalidRequestsHash(suggestedBlock.Header.RequestsHash, processedBlock.Header.RequestsHash);
         }
 
-        for (int i = 0; i < processedBlock.Transactions.Length; i++)
+        if (receipts.Length != processedBlock.Transactions.Length)
         {
-            if (receipts[i].Error is not null && receipts[i].GasUsed == 0 && receipts[i].Error == "invalid")
+            if (_logger.IsWarn) _logger.Warn($"- receipt count mismatch: expected {processedBlock.Transactions.Length} receipts to match transaction count, got {receipts.Length}");
+            error ??= BlockErrorMessages.ReceiptCountMismatch(processedBlock.Transactions.Length, receipts.Length);
+        }
+        else
+        {
+            for (int i = 0; i < processedBlock.Transactions.Length; i++)
             {
-                if (_logger.IsWarn) _logger.Warn($"- invalid transaction {i}");
-                error ??= BlockErrorMessages.InvalidTxInBlock(i);
+                if (receipts[i].Error is not null && receipts[i].GasUsed == 0 && receipts[i].Error == "invalid")
+                {
+                    if (_logger.IsWarn) _logger.Warn($"- invalid transaction {i}");
+                    error ??= BlockErrorMessages.InvalidTxInBlock(i);
+                }
             }
         }
 

src/Nethermind/Nethermind.Core/Messages/BlockErrorMessages.cs

@@ -149,4 +149,7 @@ public static string InvalidDepositEventLayout(string error) =>
 
     public static string ExceededBlockSizeLimit(int limit) =>
         $"ExceededBlockSizeLimit: Exceeded block size limit of {limit} bytes.";
+
+    public static string ReceiptCountMismatch(int expectedCount, int actualCount) =>
+        $"ReceiptCountMismatch: Expected {expectedCount} receipts to match transaction count, but got {actualCount}.";
 }