tpl/urls: Return empty string when JoinPath has zero args

tpl/urls/urls.go

@@ -187,16 +187,19 @@ func (ns *Namespace) AbsLangURL(s any) (template.HTML, error) {
 }
 
 // JoinPath joins the provided elements into a URL string and cleans the result
-// of any ./ or ../ elements.
+// of any ./ or ../ elements. If the argument list is empty, JoinPath returns
+// an empty string.
 func (ns *Namespace) JoinPath(elements ...any) (string, error) {
 
+	if len(elements) == 0 {
+		return "", nil
+	}
+
 	var selements []string
 	for _, e := range elements {
 		switch v := e.(type) {
 		case []string:
-			for _, e := range v {
-				selements = append(selements, e)
-			}
+			selements = append(selements, v...)
 		case []any:
 			for _, e := range v {
 				se, err := cast.ToStringE(e)