lexer: add Hint to Error, which is expanded as "%s" instead of "%q"

Signed-off-by: Alejandro Mery <amery@jpi.io>

lexer/error.go

@@ -29,21 +29,23 @@ type Error struct {
 	Err     error
 }
 
-func (err Error) Error() string {
-	var s []string
-	var prefix string
-
+func (err Error) prefix() string {
 	switch {
 	case err.Line > 0 || err.Column > 0:
 		if err.Filename != "" {
-			prefix = fmt.Sprintf("%s:%v:%v", err.Filename, err.Line, err.Column)
-		} else {
-			prefix = fmt.Sprintf("%v:%v", err.Line, err.Column)
+			return fmt.Sprintf("%s:%v:%v", err.Filename, err.Line, err.Column)
 		}
-	case err.Filename != "":
-		prefix = err.Filename
-	}
 
+		return fmt.Sprintf("%v:%v", err.Line, err.Column)
+	default:
+		return err.Filename
+	}
+}
+
+func (err Error) Error() string {
+	var s []string
+
+	prefix := err.prefix()
 	if prefix != "" {
 		s = append(s, prefix)
 	}