Small, hacky Minetest utility to get rid of "unknown entities" as they are activated

mt_unknown_entity_remove.lua

--[[
	Small, hacky Minetest utility to get rid of "unknown entities" as they are activated. Licensed under CC0.

	Caveat: `/spawnentity <name>` will fail with "<name> failed to spawn" rather than "Cannot spawn an unknown entity."
	for unknown entities as the unknown entity will immediately be removed inside `on_activate`.
]]
setmetatable(minetest.registered_entities, {
	__index = function(_, name)
		-- Default entity def if `minetest.registered_entities[name]` would otherwise be `nil`
		-- Necessarily leads to `minetest.registered_entities[name]` being truthy for unknown entities as well
		local def = {
			on_activate = function(self, staticdata)
				minetest.log("warning",
					("Removing entity %s at %s with staticdata %q")
					:format(name, minetest.pos_to_string(self.object:get_pos(), 2), staticdata))
				self.object:remove()
			end
		}
		def.__index = def
		return def
	end
})