[krb5-auth-dialog] kerberos: Guard against multiple unrefs

[Guido Günther <guidog src gnome org>]

commit 437a01b86b4c995f901c02adc46162a599cdd46a
Author: Guido Günther <agx sigxcpu org>
Date:   Thu Oct 13 14:05:50 2022 +0200

    kerberos: Guard against multiple unrefs
    
    We only want to free resources once

 src/ka-kerberos.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/src/ka-kerberos.c b/src/ka-kerberos.c
index 12697cc..3db6c0d 100644
--- a/src/ka-kerberos.c
+++ b/src/ka-kerberos.c
@@ -1058,8 +1058,7 @@ ka_kerberos_init (KaApplet *applet)
 gboolean
 ka_kerberos_destroy (void)
 {
-    if (ccache_monitor)
-        g_object_unref (ccache_monitor);
+    g_clear_object (&ccache_monitor);
 
     ka_krb5_context_free ();
     return TRUE;