- O(n) efficiency walk of item entities
- Honor stack family merging, e.g. differing lux levels combine
Since the new walk should be much more efficient, the need to
handle "extremal" cases specially, e.g. creation of a multi-stack
ent, is probably unnecessary. Remove it from the task list,
barring any future evidence that it's still relevant.
Some time in the 5.3 dev stream (docs updated at
217f3a42), object refs started being invalidated
immediately on calling obj:remove(), such that
obj:get_pos() starts to return nil instead of the object's
last known position.
This can cause some crashes in NodeCore, where we
assume that our object is still valid (or usable as if it
were still valid) even though we're looping through
handlers and any one of them may have remove()d the
object before other handlers get a chance to fire.
Instead, just watch for unexpected nil returns from
functions we expect would never return nil (e.g.
get_pos or get_properties) and return if we hit one.
We can assume all other calls will be non-nil after that
one, as long as we stay in the same function flow.
