logind-dbus: avoid assertion on HandlePowerKey=factory-reset

The factory-reset action is handled together with the various
sleep/shutdown actions, but its not either one.

Fixes #39385

src/login/logind-dbus.c

@@ -1946,6 +1946,11 @@ static int send_prepare_for(Manager *m, const HandleActionData *a, bool _active)
 
         assert(m);
         assert(a);
+
+        /* Only sleep/shutdown actions emit a signal */
+        if (a->inhibit_what < 0)
+                return 0;
+
         assert(IN_SET(a->inhibit_what, INHIBIT_SHUTDOWN, INHIBIT_SLEEP));
 
         /* We need to send both old and new signal for backward compatibility. The newer one allows clients
@@ -2163,6 +2168,7 @@ int bus_manager_shutdown_or_sleep_now_or_later(
 
         delayed =
                 m->inhibit_delay_max > 0 &&
+                a->inhibit_what >= 0 &&
                 manager_is_inhibited(m, a->inhibit_what, NULL, MANAGER_IS_INHIBITED_CHECK_DELAY, UID_INVALID, NULL);
 
         if (delayed)