1 files changed, 15 insertions, 13 deletions
diff --git a/object/signature/parse.go b/object/signature/parse.go
index e633f017..23c378f3 100644
--- a/object/signature/parse.go
+++ b/object/signature/parse.go
@@ -2,24 +2,26 @@ package signature
 
 import (
 	"bytes"
-	"fmt"
 	"strconv"
 
 	"codeberg.org/lindenii/furgit/internal/intconv"
 )
 
+// ErrInvalidSignature indicates an attempt to parse an invalid signature.
+var ErrInvalidSignature = errors.New("object: signature: invalid signature")
+
 // Parse parses a canonical Git signature line.
 //
 // Labels: Life-Independent.
 func Parse(line []byte) (*Signature, error) {
 	lt := bytes.IndexByte(line, '<')
 	if lt < 0 {
-		return nil, fmt.Errorf("%w: missing opening <", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	gtRel := bytes.IndexByte(line[lt+1:], '>')
 	if gtRel < 0 {
-		return nil, fmt.Errorf("%w: missing closing >", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	gt := lt + 1 + gtRel
@@ -29,24 +31,24 @@ func Parse(line []byte) (*Signature, error) {
 
 	rest := line[gt+1:]
 	if len(rest) == 0 || rest[0] != ' ' {
-		return nil, fmt.Errorf("%w: missing timestamp separator", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	rest = rest[1:]
 
 	before, after, ok := bytes.Cut(rest, []byte{' '})
 	if !ok {
-		return nil, fmt.Errorf("%w: missing timezone separator", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	when, err := strconv.ParseInt(string(before), 10, 64)
 	if err != nil {
-		return nil, fmt.Errorf("object: signature: invalid timestamp: %w", err)
+		return nil, ErrInvalidSignature
 	}
 
 	tz := after
 	if len(tz) < 5 {
-		return nil, fmt.Errorf("%w: invalid timezone encoding", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	sign := 1
@@ -56,32 +58,32 @@ func Parse(line []byte) (*Signature, error) {
 		sign = -1
 	case '+':
 	default:
-		return nil, fmt.Errorf("%w: invalid timezone sign", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	hh, err := strconv.Atoi(string(tz[1:3]))
 	if err != nil {
-		return nil, fmt.Errorf("object: signature: invalid timezone hours: %w", err)
+		return nil, ErrInvalidSignature
 	}
 
 	mm, err := strconv.Atoi(string(tz[3:5]))
 	if err != nil {
-		return nil, fmt.Errorf("object: signature: invalid timezone minutes: %w", err)
+		return nil, ErrInvalidSignature
 	}
 
 	if hh < 0 || hh > 23 {
-		return nil, fmt.Errorf("%w: invalid timezone hours range", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	if mm < 0 || mm > 59 {
-		return nil, fmt.Errorf("%w: invalid timezone minutes range", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	total := int64(hh)*60 + int64(mm)
 
 	offset, err := intconv.Int64ToInt32(total)
 	if err != nil {
-		return nil, fmt.Errorf("%w: timezone overflow", ErrInvalidSignature)
+		return nil, ErrInvalidSignature
 	}
 
 	if sign < 0 {