[17] diggy_cave_collapse: changes to on_built_tile

[mheguy]

In 0.17 on_player_built_tile the return of an item is no longer certain.

RedMew/map_gen/maps/diggy/feature/diggy_cave_collapse.lua

Line 218 in 76871ee

local function on_built_tile(surface, new_tile, tiles)

[adrianvanderwal]

It seems item was never used in the first place?

The parameters used in the Event have stayed the same.

Event.add(
        defines.events.on_player_built_tile,
        function(event)
            on_built_tile(game.surfaces[event.surface_index], event.item, event.tiles)
        end
    )

https://lua-api.factorio.com/latest/events.html#on_player_built_tile

[mheguy]

I think you're misunderstanding what I'm saying.
In the API:

on_player_built_tile

Called after a player builds tiles. 
Contains
player_index :: uint
surface_index :: uint: The surface the tile(s) were built on.
tiles :: array of OldTileAndPosition: The position data.
item :: LuaItemPrototype (optional): The item type used to build the tiles
stack :: LuaItemStack (optional): The stack used to build the tiles (may be empty if all of the items where used to build the tiles).

item is an optional return. Which means we should catch the case of event.item being nil.

[grilledham]

Do we know when event.item is nil is it to accommodate mods that might allow building tiles without an item in hand? Or does it happen when you place the last item in the stack?

[mheguy]

We don't know. I can try summoning @Bilka2 :)

[Bilka2]

Item is nil when using the tile editor (editor controller) to place tiles. It's also nil when the editor controller instant-builds blueprints (and that contains a tile).