GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed
aborting...

Program received signal SIGABRT, Aborted.
0xb806e430 in __kernel_vsyscall ()
(gdb) bt
#0  0xb806e430 in __kernel_vsyscall ()
#1  0xb7de26d0 in raise () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7de4098 in abort () from /lib/tls/i686/cmov/libc.so.6
#3  0xb7f5deac in IA__g_logv (log_domain=0xb8005e7c "GLib-GObject", log_level=G_LOG_LEVEL_CRITICAL, format=0xb7f95bf1 "%s: assertion `%s' failed", 
    args1=0xbff8c39c "�w") at /build/buildd/glib2.0-2.20.1/glib/gmessages.c:506
#4  0xb7f5dee6 in IA__g_log (log_domain=0xb8005e7c "GLib-GObject", log_level=G_LOG_LEVEL_CRITICAL, format=0xb7f95bf1 "%s: assertion `%s' failed")
    at /build/buildd/glib2.0-2.20.1/glib/gmessages.c:526
#5  0xb7f5e14b in IA__g_return_if_fail_warning (log_domain=0xb8005e7c "GLib-GObject", pretty_function=0xb80077ea "g_object_unref", 
    expression=0xb8006ada "G_IS_OBJECT (object)") at /build/buildd/glib2.0-2.20.1/glib/gmessages.c:541
#6  0xb7fdfcdc in IA__g_object_unref (_object=0x9ade6c0) at /build/buildd/glib2.0-2.20.1/gobject/gobject.c:2371
#7  0x08049420 in main_main (args=0xbff8c4d4, args_length1=1) at main.vala.c:285
#8  0x08049456 in main (argc=1, argv=0xbff8c4d4) at main.vala:18
(gdb) 
