[balsa/wip/gtk4] balsa-message: check for NULL return

[Peter Bloomfield <peterb src gnome org>]

commit 158666c9ed8da6af1e5c2b5c9ff530f8883aca75
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Sat Sep 28 13:51:27 2019 -0400

    balsa-message: check for NULL return
    
    from gtk_icon_theme_load_icon()

 src/balsa-message.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/src/balsa-message.c b/src/balsa-message.c
index 214b91971..5fed6067c 100644
--- a/src/balsa-message.c
+++ b/src/balsa-message.c
@@ -2693,7 +2693,7 @@ get_crypto_content_icon(LibBalsaMessageBody * body, const gchar * content_type,
                        gchar ** icon_title)
 {
     GdkPaintable *paintable;
-    GdkPixbuf *icon;
+    GdkPixbuf *icon = NULL;
     gchar * new_title;
     const gchar * icon_name;
     gpgme_error_t status;
@@ -2709,8 +2709,10 @@ get_crypto_content_icon(LibBalsaMessageBody * body, const gchar * content_type,
 
     paintable =
         gtk_icon_theme_load_icon(gtk_icon_theme_get_default(), icon_name, 24, 0, NULL);
-    icon = gdk_pixbuf_get_from_texture(GDK_TEXTURE(paintable));
-    g_object_unref(paintable);
+    if (paintable != NULL) {
+        icon = gdk_pixbuf_get_from_texture(GDK_TEXTURE(paintable));
+        g_object_unref(paintable);
+    }
 
     if (!icon_title)
         return icon;