imo it would make sense to add the prototype-api.json and runtime-api.json either to the factorio-data github repo or to a separate github repo so that all machine-readable documentation / data about the game is in one place and can be added to projects for example using a git submodule instead of ...

aaah okay, thank you ^^
did not realize transport lines existed

i think it would still be good to make get_max_inventory_index return 0 instead so this kind of confusion doesn't happen

so I can insert, check for and remove items on a belt, but it just isn't possible to modify for example the spoil percent of an existing item?
or can i just remove one item and insert it again with a changed parameter? this would probably not preserve item order and lane side

my problem is not that there are some inventories that are nil, but all inventories with indices between 1 and 8 (i haven't looked at other indices) are nil, so there is no way for me to access the inventory of a transport belt. is that just not possible at all? or have i missed something and there ...

I'm trying to make a special conveyor belt that modifies its contents' spoilage, but this is also the same with the vanilla/base transport belts.

Script to test this out:
Iterating over all inventories just like the example in the LuaControl::get_max_inventory_index documentation

--control.lua ...