state: always deserialize LastGasPerVote

It can be non-zero even if VoteTo is NULL. Fixes state diff with 3.6.0:

  block 41660: value mismatch for key +////xTrvgat3qG/w8hQoD/I4MgUz6rygA==: QQQhAS8hA7yiAAAhAA== vs QQQhAS8hA7yiAAAhB+POSWfBCAE=

Related to #2844.

Signed-off-by: Roman Khimov <roman@nspcc.ru>

pkg/core/state/native_state.go

@@ -148,17 +148,17 @@ func (s *NEOBalance) FromStackItem(item stackitem.Item) error {
 	s.BalanceHeight = uint32(h.Int64())
 	if _, ok := structItem[2].(stackitem.Null); ok {
 		s.VoteTo = nil
-		return nil
-	}
-	bs, err := structItem[2].TryBytes()
-	if err != nil {
-		return fmt.Errorf("invalid public key stackitem: %w", err)
-	}
-	pub, err := keys.NewPublicKeyFromBytes(bs, elliptic.P256())
-	if err != nil {
-		return fmt.Errorf("invalid public key bytes: %w", err)
+	} else {
+		bs, err := structItem[2].TryBytes()
+		if err != nil {
+			return fmt.Errorf("invalid public key stackitem: %w", err)
+		}
+		pub, err := keys.NewPublicKeyFromBytes(bs, elliptic.P256())
+		if err != nil {
+			return fmt.Errorf("invalid public key bytes: %w", err)
+		}
+		s.VoteTo = pub
 	}
-	s.VoteTo = pub
 	if len(structItem) >= 4 {
 		lastGasPerVote, err := structItem[3].TryInteger()
 		if err != nil {

pkg/core/state/native_state_test.go

@@ -1,8 +1,10 @@
 package state
 
 import (
+	"math/big"
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 	"github.com/stretchr/testify/require"
 )
@@ -47,6 +49,36 @@ func TestNEP17BalanceFromBytesInvalid(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestNEOBalanceSerialization(t *testing.T) {
+	var b = NEOBalance{
+		NEP17Balance:  NEP17Balance{*big.NewInt(100500)},
+		BalanceHeight: 42,
+	}
+	si, err := b.ToStackItem()
+	require.NoError(t, err)
+
+	var bb NEOBalance
+	require.NoError(t, bb.FromStackItem(si))
+	require.Equal(t, b, bb)
+
+	b.VoteTo, err = keys.NewPublicKeyFromString("03b209fd4f53a7170ea4444e0cb0a6bb6a53c2bd016926989cf85f9b0fba17a70c")
+	require.NoError(t, err)
+	b.LastGasPerVote = *big.NewInt(100500)
+
+	si, err = b.ToStackItem()
+	require.NoError(t, err)
+	bb = NEOBalance{}
+	require.NoError(t, bb.FromStackItem(si))
+	require.Equal(t, b, bb)
+
+	b.VoteTo = nil
+	si, err = b.ToStackItem()
+	require.NoError(t, err)
+	bb = NEOBalance{}
+	require.NoError(t, bb.FromStackItem(si))
+	require.Equal(t, b, bb)
+}
+
 func BenchmarkNEP17BalanceBytes(b *testing.B) {
 	var bl NEP17Balance
 	bl.Balance.SetInt64(0x12345678910)