Fix the following assertion failure:

 "nm_assert(NM_DEVICE_GET_PRIVATE(self)->act_request.obj);"

  0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
  1  __GI_abort () at abort.c:79
  2  g_assertion_message () at gtestutils.c:2533
  3  g_assertion_message_expr () at gtestutils.c:2556
  4  activation_source_invoke_or_schedule (self=0x55b543884610 [NMDeviceBridge], func=0x55b542e8c940 <activate_stage3_ip_config>, do_sync=0) at src/core/devices/nm-device.c:8854
  5  nm_device_set_carrier (self=0x55b543884610 [NMDeviceBridge], carrier=1) at src/core/devices/nm-device.c:6217
  6  device_link_changed (user_data=user_data@entry=0x55b543884610) at src/core/devices/nm-device.c:6479
  7  g_idle_dispatch (source=0x55b5438577d0, callback=0x55b542e95980 <device_link_changed>, user_data=0x55b543884610) at gmain.c:5579
  8  g_main_dispatch (context=0x55b543719bc0) at gmain.c:3193
  9  g_main_context_dispatch (context=context@entry=0x55b543719bc0) at gmain.c:3873
  10 g_main_context_iterate (context=0x55b543719bc0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at gmain.c:3946