Unify error messages

category.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"html"
 )
@@ -29,17 +28,17 @@ func (c *Category) SetLabel(label string) {
 // error.
 func (c *Category) Check() error {
 	if c.Term == "" {
-		return errors.New("term attribute of category empty")
+		return fmt.Errorf("term attribute of category %v empty", c)
 	}
 
 	if c.Scheme != "" {
 		if !isValidIRI(c.Scheme) {
-			return fmt.Errorf("scheme attribute %v of category not correctly formatted", c.Scheme)
+			return fmt.Errorf("scheme attribute of category %v not correctly formatted", c)
 		}
 	}
 
 	if !isCorrectlyEscaped(c.Label) {
-		return fmt.Errorf("label attribute %v of category not correctly escaped", c.Label)
+		return fmt.Errorf("label attribute of category %v not correctly escaped", c)
 	}
 
 	return nil