[gnome-control-center/gnome-41] network: fix critical when opening VPN details page

[Robert Ancell <rancell src gnome org>]

commit 522074ec7ca4d195ec6177bca4e0c34992ad0dad
Author: Michael Catanzaro <mcatanzaro redhat com>
Date:   Fri Nov 5 16:25:58 2021 -0500

    network: fix critical when opening VPN details page
    
    I was seeing this critical when opening the VPN details page:
    
    (gnome-control-center:78888): nm-CRITICAL **: 16:26:21.689: ((src/libnm-client-impl/nm-device.c:1299)): 
assertion '<dropped>' failed
    
    It probably broke in 551d72280bbc9479a81697e2d888a77a64538b27. The code
    above and below expects self->device may be NULL, so let's add a
    NULL check here.

 panels/network/connection-editor/ce-page-details.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/panels/network/connection-editor/ce-page-details.c 
b/panels/network/connection-editor/ce-page-details.c
index 390851569..782617921 100644
--- a/panels/network/connection-editor/ce-page-details.c
+++ b/panels/network/connection-editor/ce-page-details.c
@@ -297,7 +297,9 @@ connect_details_page (CEPageDetails *self)
         gtk_widget_set_visible (GTK_WIDGET (self->speed_heading_label), speed_label != NULL);
         gtk_widget_set_visible (GTK_WIDGET (self->speed_label), speed_label != NULL);
 
-        hw_address = nm_device_get_hw_address (self->device);
+        if (self->device)
+            hw_address = nm_device_get_hw_address (self->device);
+
         gtk_label_set_label (self->mac_label, hw_address);
         gtk_widget_set_visible (GTK_WIDGET (self->mac_heading_label), hw_address != NULL);
         gtk_widget_set_visible (GTK_WIDGET (self->mac_label), hw_address != NULL);