Placing upside-down slabs can crash server

[ShadowNinja]

If you place a slab on the side of an upside-down slab and the position where the new slab should be placed is already used(for example by a mesecon)

the server will crash with the error:
.../minetest/games/minetest_game/mods/stairs/init.lua:184: attempt to index local 'ret' (a nil value)

and at line 184 we have:

local fakestack = ItemStack("stairs:slab_" .. subname.."upside_down")
local ret = minetest.item_place(fakestack, placer, pointed_thing)
if ret:is_empty() then    --line 184

shoudn't this be:
if ret and ret:is_empty() then

[PilzAdam]

I wonder if its rather a bug in minetest.item_place. There is no documentation of the return value of it in doc/lua-api.txt but I think it should always return an ItemStack.

[ShadowNinja]

@PilzAdam: Should I post an issue with the engine then?

[PilzAdam]

@ShadowNinja: Yea, something like "Inconsistent return value of minetest.item_place()".