[glib: 17/19] gtype: Fix pointer being dereferenced despite NULL check

[Philip Withnall <pwithnall src gnome org>]

commit 5419228f632af830d9117c142a1c7c1a9708cc08
Author: Egor Bychin <e bychin drweb com>
Date:   Mon Oct 11 14:26:20 2021 +0300

    gtype: Fix pointer being dereferenced despite NULL check

 gobject/gtype.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/gobject/gtype.c b/gobject/gtype.c
index 34f62ecba..26ec30b7b 100644
--- a/gobject/gtype.c
+++ b/gobject/gtype.c
@@ -3159,11 +3159,14 @@ g_type_class_peek_parent (gpointer g_class)
   g_return_val_if_fail (g_class != NULL, NULL);
   
   node = lookup_type_node_I (G_TYPE_FROM_CLASS (g_class));
+
+  g_return_val_if_fail (node != NULL, NULL);
+
   /* We used to acquire a read lock here. That is not necessary, since 
    * parent->data->class.class is constant as long as the derived class
    * exists. 
    */
-  if (node && node->is_classed && node->data && NODE_PARENT_TYPE (node))
+  if (node->is_classed && node->data && NODE_PARENT_TYPE (node))
     {
       node = lookup_type_node_I (NODE_PARENT_TYPE (node));
       class = node->data->class.class;