Imagine if recycling recipes required a fluid. Say you specify the fluid as 2nd ingredient:

data:extend({{
type = "recipe",
...
ingredients = {
{type = "item", name = item_name, amount = 1},
{type = "fluid", name = "promethium-emulsion", amount = fluid_requirement}
},
...
}})

Game would ...

Been on multiplayer with a friend for a while and eventually we ran into slight UPS problems. Friend decided to install this mod https://mods.factorio.com/mod/FPS_Friendly_Thrusters.
Now i'm running into an always reproducible crash, for some reason only on that multiplayer save. Beyond that we also ...