[MIRROR] bunch of runtimes (#12664)

Co-authored-by: Kashargul <144968721+Kashargul@users.noreply.github.com>
Co-authored-by: Cameron Lennox <killer65311@gmail.com>

code/modules/nifsoft/nif.dm

@@ -104,6 +104,7 @@ You can also set the stat of a NIF to NIF_TEMPFAIL without any issues to disable
 
 /obj/item/nif/proc/unregister_human()
 	UnregisterSignal(human, COMSIG_MOB_DEATH)
+	human.nif = null
 
 //Destructor cleans up references
 /obj/item/nif/Destroy()

code/modules/nifsoft/nif_tgui.dm

@@ -29,6 +29,11 @@
 		return COMPONENT_INCOMPATIBLE
 	. = ..()
 
+/datum/component/nif_menu/Destroy(force)
+	if(screen_icon)
+		QDEL_NULL(screen_icon)
+	. = ..()
+
 /datum/component/nif_menu/RegisterWithParent()
 	. = ..()
 	RegisterSignal(parent, COMSIG_MOB_CLIENT_LOGIN, PROC_REF(create_mob_button))