Unify error messages

person.go

@@ -1,7 +1,6 @@
 package atom
 
 import (
-	"errors"
 	"fmt"
 	"net/mail"
 )
@@ -33,25 +32,25 @@ func (p *Person) AddExtension(e *ExtensionElement) {
 // error.
 func (p *Person) Check() error {
 	if p.Name == "" {
-		return errors.New("name element of person element empty")
+		return fmt.Errorf("name element of person %v empty", p)
 	}
 
 	if p.URI != "" {
 		if !isValidIRI(p.URI) {
-			return fmt.Errorf("uri element of person %v not correctly formatted", p.Name)
+			return fmt.Errorf("uri element of person %v not correctly formatted", p)
 		}
 	}
 
 	if p.Email != "" {
 		if _, err := mail.ParseAddress(string(p.Email)); err != nil {
-			return fmt.Errorf("email element of person %v not correctly formatted", p.Name)
+			return fmt.Errorf("email element of person %v not correctly formatted", p)
 		}
 	}
 
 	if p.Extensions != nil {
 		for i, e := range p.Extensions {
 			if err := e.Check(); err != nil {
-				return fmt.Errorf("extension element %v of person %v: %v", i, p.Name, err)
+				return fmt.Errorf("extension element %v of person %v: %v", i, p, err)
 			}
 		}
 	}