🐛 Fixed returned language in User util

utils_user.go

@@ -3,17 +3,17 @@ package telegram
 import "golang.org/x/text/language"
 
 // Language parse LanguageCode of current user and returns language.Tag.
-func (u *User) Language() *language.Tag {
+func (u *User) Language() language.Tag {
 	if u == nil {
-		return nil
+		return language.Und
 	}
 
 	tag, err := language.Parse(u.LanguageCode)
 	if err != nil {
-		return nil
+		return language.Und
 	}
 
-	return &tag
+	return tag
 }
 
 // FullName returns the full name of user or FirstName if LastName is not