[balsa] Assert that the BalsaWindow is not NULL

[Peter Bloomfield <peterb src gnome org>]

commit e04dace5fd82ad66539575adc86a2eedbe9dfa56
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Wed Jun 28 18:02:08 2017 -0400

    Assert that the BalsaWindow is not NULL
    
        * src/main-window.c (bw_action_set_enabled): assert that the
        BalsaWindow is not NULL.

 ChangeLog         |    7 +++++++
 src/main-window.c |    2 ++
 2 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 20fcac8..e872b75 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 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
+       BalsaWindow is not NULL.
+
+2017-06-28  Peter Bloomfield  <pbloomfield bellsouth net>
+
        Handle GError pointer more carefully
 
        * libbalsa/body.c
diff --git a/src/main-window.c b/src/main-window.c
index 118cba1..4c3d5c2 100644
--- a/src/main-window.c
+++ b/src/main-window.c
@@ -769,6 +769,8 @@ bw_action_set_enabled(BalsaWindow * window,
 {
     GAction *action;
 
+    g_assert(window != NULL);
+
     /* Is the window being destroyed? */
     if (window->preview == NULL)
         return;