Address nkcr's comments

blockchain/skipchain/ops.go

@@ -13,6 +13,8 @@ import (
 	"golang.org/x/xerrors"
 )
 
+// operations implements helper functions that can be used by the handlers for
+// common operations.
 type operations struct {
 	logger       zerolog.Logger
 	encoder      encoding.ProtoMarshaler

consensus/cosipbft/mod.go

@@ -120,8 +120,11 @@ func (c *Consensus) Store(in consensus.Chain) error {
 		return xerrors.Errorf("couldn't read latest chain: %v", err)
 	}
 
+	store := false
 	for _, link := range chain.links {
-		if last == nil || bytes.Equal(last.To, link.from[:]) {
+		store = store || last == nil || bytes.Equal(last.To, link.from[:])
+
+		if store {
 			linkpb, err := c.encoder.Pack(link)
 			if err != nil {
 				return xerrors.Errorf("couldn't pack link: %v", err)
@@ -131,8 +134,6 @@ func (c *Consensus) Store(in consensus.Chain) error {
 			if err != nil {
 				return xerrors.Errorf("couldn't store link: %v", err)
 			}
-
-			last = nil
 		}
 	}
 

ledger/byzcoin/roster/task.go

@@ -66,7 +66,7 @@ func (t clientTask) GetChangeSet() viewchange.ChangeSet {
 		if removals[i] == removals[i+1] {
 			removals = append(removals[:i], removals[i+1:]...)
 		} else {
-			// Only moves to the next when all occurances of the same index are
+			// Only moves to the next when all occurences of the same index are
 			// removed.
 			i++
 		}
@@ -296,8 +296,7 @@ func (f TaskManager) FromProto(in proto.Message) (basic.ServerTask, error) {
 
 	player, err := f.unpackPlayer(pb.GetAddr(), pb.GetPublicKey())
 	if err != nil {
-		// The error is not wrap to avoid redundancy with the private function.
-		return nil, err
+		return nil, xerrors.Errorf("couldn't unpack player: %v", err)
 	}
 
 	task := serverTask{

ledger/byzcoin/roster/task_test.go

@@ -211,7 +211,8 @@ func TestTaskManager_FromProto(t *testing.T) {
 	factory = NewRosterFactory(fake.AddressFactory{}, fake.NewBadPublicKeyFactory())
 	manager = NewTaskManager(factory, nil)
 	_, err = manager.FromProto(&Task{Addr: []byte{}, PublicKey: &any.Any{}})
-	require.EqualError(t, err, "couldn't decode public key: fake error")
+	require.EqualError(t, err,
+		"couldn't unpack player: couldn't decode public key: fake error")
 }
 
 // -----------------------------------------------------------------------------