Some GLib-GObject-CRITICAL when launching lxpanel

[mtasaka]

With the same environ as #118 :

• libfm: 1.4.1 7e575d1
• lxpanel git head lxde/lxpanel@4dec3d0
• GLib 2.88.0

Launching $ lxpanel --profile LXDE shows some GLib-GObject-CRITICAL warnings as

(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:18.961: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:18.964: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:18.964: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:18.991: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.006: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.008: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.009: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.014: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.015: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.028: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.028: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.218: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
(lxpanel:183866): GLib-GObject-CRITICAL **: 16:18:19.221: g_object_unref: assertion 'G_IS_OBJECT (object)' failed