Check error of g_dbus_proxy_new_sync call

Otherwise errors pile up and we crash later on.

src/main.c

@@ -68,12 +68,14 @@ shell_dbus_acquire_name (GDBusProxy  *bus,
                                                        NULL, /* cancellable */
                                                        &error)))
     {
-      g_printerr ("failed to acquire %s: %s\n", name, error->message);
+      g_printerr ("failed to acquire %s: %s\n", name, error ? error->message : "");
+      g_clear_error (&error);
       if (!fatal)
         return;
       exit (1);
     }
   g_variant_get (request_name_variant, "(u)", request_name_result);
+  g_variant_unref (request_name_variant);
 }
 
 static void
@@ -130,6 +132,12 @@ shell_dbus_init (gboolean replace)
                                NULL, /* cancellable */
                                &error);
 
+  if (!bus)
+    {
+      g_printerr ("Failed to get a session bus proxy: %s", error->message);
+      exit (1);
+    }
+
   request_name_flags = G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT;
   if (replace)
     request_name_flags |= DBUS_NAME_FLAG_REPLACE_EXISTING;