* Mobs redo uses `registered_items[]` where clearly the proper table
accessed should be `registered_nodes[]`. Perhaps this magically
works, but it looks nonsensical. Switch to the use the more
sensible `registered_nodes[]` table.
* Check if node has a definition table before attempting to evaluate its
attributes.
* Define local variable to cache multiple accesses to `registered_nodes[]`
and improve readability.