Unify error messages

inlineTextContent.go

@@ -2,7 +2,6 @@ package atom
 
 import (
 	"encoding/xml"
-	"errors"
 	"fmt"
 )
 
@@ -43,7 +42,7 @@ func (i *InlineTextContent) getType() string { return i.Type }
 // returns an error.
 func (i *InlineTextContent) Check() error {
 	if i.Type != "" && i.Type != "text" && i.Type != "html" {
-		return errors.New("type attribute of inline text content must be text or html if not omitted")
+		return fmt.Errorf("type attribute of inline text content %v must be text or html if not omitted", i)
 	}
 
 	return nil