stackitem: fix Buffer deserialization

Fix incorrect application log for transaction in N3 testnet
8eb4076f1f1c07e693eda7e810779488a2d2b50aba9b727fd237cbc3adbec9e9

Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>

cli/nep11_test.go

@@ -312,7 +312,7 @@ func TestNEP11_OwnerOf_BalanceOf_Transfer(t *testing.T) {
 		ScriptHash: verifyH,
 		Name:       "OnNEP11Payment",
 		Item: stackitem.NewArray([]stackitem.Item{
-			stackitem.NewByteArray(nftOwnerHash.BytesBE()),
+			stackitem.NewBuffer(nftOwnerHash.BytesBE()),
 			stackitem.NewBigInteger(big.NewInt(1)),
 			stackitem.NewByteArray(tokenID1),
 			stackitem.NewByteArray([]byte("some_data")),

pkg/vm/stackitem/serialization.go

@@ -129,7 +129,10 @@ func decodeBinaryStackItem(r *io.BinReader, allowInvalid bool) Item {
 	switch t {
 	case ByteArrayT, BufferT:
 		data := r.ReadVarBytes(MaxSize)
-		return NewByteArray(data)
+		if t == ByteArrayT {
+			return NewByteArray(data)
+		}
+		return NewBuffer(data)
 	case BooleanT:
 		var b = r.ReadBool()
 		return NewBool(b)