filterx/object-metrics-labels: fix leaking pre-transform new_value in set_sub()

Signed-off-by: Attila Szakacs <attila.szakacs@axoflow.com>

Author: alltilla

lib/filterx/object-metrics-labels.c

@@ -128,15 +128,18 @@ _set_subscript(FilterXDict *s, FilterXObject *key, FilterXObject **new_value)
   if (!name_str || !value_str)
     return FALSE;
 
-  if (!filterx_object_is_type(*new_value, &FILTERX_TYPE_NAME(string)))
-    *new_value = filterx_string_new(value_str, -1);
-
   StatsClusterLabel label = stats_cluster_label(g_strndup(name_str, name_len), g_strndup(value_str, value_len));
   g_array_append_val(self->labels, label);
 
   self->sorted = FALSE;
   self->deduped = FALSE;
 
+  if (!filterx_object_is_type(*new_value, &FILTERX_TYPE_NAME(string)))
+    {
+      filterx_object_unref(*new_value);
+      *new_value = filterx_string_new(value_str, value_len);
+    }
+
   scratch_buffers_reclaim_marked(marker);
   return TRUE;
 }