[balsa] Assert that a child widget is non-NULL

[Peter Bloomfield <peterb src gnome org>]

commit 19ada16efc1f8a16e83f97fb9ed5e620585211d9
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Wed Jun 28 21:41:53 2017 -0400

    Assert that a child widget is non-NULL
    
        * src/balsa-mime-widget-message.c (foreach_label): assert that
        the widget is non-NULL.

 ChangeLog                       |    7 +++++++
 src/balsa-mime-widget-message.c |    2 ++
 2 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index e872b75..e159707 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2017-06-28  Peter Bloomfield  <pbloomfield bellsouth net>
 
+       Assert that a child widget is non-NULL
+
+       * src/balsa-mime-widget-message.c (foreach_label): assert that
+       the widget is non-NULL.
+
+2017-06-28  Peter Bloomfield  <pbloomfield bellsouth net>
+
        Assert that the BalsaWindow is not NULL
 
        * src/main-window.c (bw_action_set_enabled): assert that the
diff --git a/src/balsa-mime-widget-message.c b/src/balsa-mime-widget-message.c
index 7adfcde..7da9371 100644
--- a/src/balsa-mime-widget-message.c
+++ b/src/balsa-mime-widget-message.c
@@ -676,6 +676,8 @@ add_header_address_list(BalsaMessage * bm, GtkGrid * grid,
 static void
 foreach_label(GtkWidget * widget, LibBalsaMessageBody * part)
 {
+    g_assert(widget != NULL);
+
     if (GTK_IS_CONTAINER(widget))
         gtk_container_foreach(GTK_CONTAINER(widget),
                               (GtkCallback) foreach_label, part);