Unify error messages

link.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"strings"
 )
@@ -27,28 +26,28 @@ func NewLink(href string) *Link {
 // error.
 func (l *Link) Check() error {
 	if l.Href == "" {
-		return errors.New("href attribute of link empty")
+		return fmt.Errorf("href attribute of link %v empty", l)
 	} else {
 		if !isValidIRI(l.Href) {
-			return fmt.Errorf("href attribute %v of link not correctly formatted", l.Href)
+			return fmt.Errorf("href attribute of link %v not correctly formatted", l)
 		}
 	}
 
 	if l.Rel != "" {
 		if strings.Contains(l.Rel, ":") && !isValidIRI(IRI(l.Rel)) {
-			return fmt.Errorf("rel attribute %v of link %v not correctly formatted", l.Rel, l.Href)
+			return fmt.Errorf("rel attribute of link %v not correctly formatted", l)
 		}
 	}
 
 	if l.Type != "" {
 		if !isValidMediaType(string(l.Type)) {
-			return fmt.Errorf("type attribute %v of link %v invalid media type", l.Type, l.Href)
+			return fmt.Errorf("type attribute of link %v invalid media type", l)
 		}
 	}
 
 	if l.HrefLang != "" {
 		if !isValidLanguageTag(l.HrefLang) {
-			return fmt.Errorf("hreflang attribute %v of link %v invalid language tag", l.Type, l.HrefLang)
+			return fmt.Errorf("hreflang attribute of link %v invalid language tag", l)
 		}
 	}