multi: fix fmt.Errorf error wrapping

Refactor fmt.Errorf usage to correctly wrap errors instead of using
non-wrapping format verbs.

chanbackup/backup.go

@@ -72,7 +72,7 @@ func FetchBackupForChan(chanPoint wire.OutPoint, chanSource LiveChannelSource,
 	// the source to obtain any extra information that we may need.
 	staticChanBackup, err := assembleChanBackup(addrSource, targetChan)
 	if err != nil {
-		return nil, fmt.Errorf("unable to create chan backup: %v", err)
+		return nil, fmt.Errorf("unable to create chan backup: %w", err)
 	}
 
 	return staticChanBackup, nil

chanbackup/backupfile.go

@@ -93,17 +93,18 @@ func (b *MultiFile) UpdateAndSwap(newBackup PackedMulti) error {
 	var err error
 	b.tempFile, err = os.Create(b.tempFileName)
 	if err != nil {
-		return fmt.Errorf("unable to create temp file: %v", err)
+		return fmt.Errorf("unable to create temp file: %w", err)
 	}
 
 	// With the file created, we'll write the new packed multi backup and
 	// remove the temporary file all together once this method exits.
 	_, err = b.tempFile.Write([]byte(newBackup))
 	if err != nil {
-		return fmt.Errorf("unable to write backup to temp file: %v", err)
+		return fmt.Errorf("unable to write backup to temp file: %w",
+			err)
 	}
 	if err := b.tempFile.Sync(); err != nil {
-		return fmt.Errorf("unable to sync temp file: %v", err)
+		return fmt.Errorf("unable to sync temp file: %w", err)
 	}
 	defer os.Remove(b.tempFileName)
 
@@ -114,7 +115,7 @@ func (b *MultiFile) UpdateAndSwap(newBackup PackedMulti) error {
 	// sure to close the current file as some OSes don't support
 	// renaming a file that's already open (Windows).
 	if err := b.tempFile.Close(); err != nil {
-		return fmt.Errorf("unable to close file: %v", err)
+		return fmt.Errorf("unable to close file: %w", err)
 	}
 
 	// Finally, we'll attempt to atomically rename the temporary file to

chanbackup/backupfile_test.go

@@ -16,7 +16,7 @@ import (
 func makeFakePackedMulti() (PackedMulti, error) {
 	newPackedMulti := make([]byte, 50)
 	if _, err := rand.Read(newPackedMulti[:]); err != nil {
-		return nil, fmt.Errorf("unable to make test backup: %v", err)
+		return nil, fmt.Errorf("unable to make test backup: %w", err)
 	}
 
 	return PackedMulti(newPackedMulti), nil

chanbackup/multi.go

@@ -92,7 +92,7 @@ func (m Multi) PackToWriter(w io.Writer, keyRing keychain.KeyRing) error {
 	// directly to the passed writer.
 	e, err := lnencrypt.KeyRingEncrypter(keyRing)
 	if err != nil {
-		return fmt.Errorf("unable to generate encrypt key %v", err)
+		return fmt.Errorf("unable to generate encrypt key %w", err)
 	}
 
 	return e.EncryptPayloadToWriter(multiBackupBuffer.Bytes(), w)
@@ -107,7 +107,7 @@ func (m *Multi) UnpackFromReader(r io.Reader, keyRing keychain.KeyRing) error {
 	// encryption keys.
 	e, err := lnencrypt.KeyRingEncrypter(keyRing)
 	if err != nil {
-		return fmt.Errorf("unable to generate encrypt key %v", err)
+		return fmt.Errorf("unable to generate encrypt key %w", err)
 	}
 	plaintextBackup, err := e.DecryptPayloadFromReader(r)
 	if err != nil {

chanbackup/pubsub.go

@@ -226,7 +226,7 @@ func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {
 	var b bytes.Buffer
 	err = newMulti.PackToWriter(&b, s.keyRing)
 	if err != nil {
-		return fmt.Errorf("unable to pack multi backup: %v", err)
+		return fmt.Errorf("unable to pack multi backup: %w", err)
 	}
 
 	// Finally, we'll swap out the old backup for this new one in a single
@@ -234,7 +234,7 @@ func (s *SubSwapper) updateBackupFile(closedChans ...wire.OutPoint) error {
 	// channels.
 	err = s.Swapper.UpdateAndSwap(PackedMulti(b.Bytes()))
 	if err != nil {
-		return fmt.Errorf("unable to update multi backup: %v", err)
+		return fmt.Errorf("unable to update multi backup: %w", err)
 	}
 
 	return nil

chanbackup/pubsub_test.go

@@ -36,7 +36,7 @@ func (m *mockSwapper) UpdateAndSwap(newBackup PackedMulti) error {
 
 	swapState, err := newBackup.Unpack(m.keyChain)
 	if err != nil {
-		return fmt.Errorf("unable to decode on disk swaps: %v", err)
+		return fmt.Errorf("unable to decode on disk swaps: %w", err)
 	}
 
 	m.swapState = swapState

chanbackup/single.go

@@ -362,7 +362,7 @@ func (s *Single) PackToWriter(w io.Writer, keyRing keychain.KeyRing) error {
 	// nonce that we used to the passed io.Reader.
 	e, err := lnencrypt.KeyRingEncrypter(keyRing)
 	if err != nil {
-		return fmt.Errorf("unable to generate encrypt key %v", err)
+		return fmt.Errorf("unable to generate encrypt key %w", err)
 	}
 	return e.EncryptPayloadToWriter(rawBytes.Bytes(), w)
 }
@@ -544,7 +544,7 @@ func (s *Single) Deserialize(r io.Reader) error {
 func (s *Single) UnpackFromReader(r io.Reader, keyRing keychain.KeyRing) error {
 	e, err := lnencrypt.KeyRingEncrypter(keyRing)
 	if err != nil {
-		return fmt.Errorf("unable to generate key decrypter %v", err)
+		return fmt.Errorf("unable to generate key decrypter %w", err)
 	}
 	plaintext, err := e.DecryptPayloadFromReader(r)
 	if err != nil {