Module:Data/sandbox

 local mt = {}

 function mt.__index(t, k)
	return function(frame)
		local success, data = pcall(mw.loadData, k)
		if not success then
			success, data = pcall(mw.loadJsonData, k)
			if not success then
				error("'" .. k .. "' is not a valid data page")
			end
		end
		for i, v in ipairs(frame.args) do
			local ty = type(data)
			if ty ~= 'table' then
				local args = {}
				for j = 1, i - 1 do
					args[j] = frame.args[j]
				end
				if frame.args.softfail then
					return '<span class="error">[[Category:Pages with failed Module:Data lookups]]Error: Tried to read index "' .. mw.text.nowiki(v) .. '" of mw.loadData("' .. mw.text.nowiki(k) .. '").' .. mw.text.nowiki(table.concat(args, '.')) .. ', which is a ' .. ty .. '</span>'
				else
					error('Tried to read index "' .. v .. '" of mw.loadData("' .. k .. '").' .. table.concat(args, '.') .. ', which is a ' .. ty)
				end
			end
			local nextdata = data[v]
			if nextdata == nil and tonumber(v) then
				data = data[tonumber(v)]
			else
				data = nextdata
			end
		end
		return data
	end
 end

 return setmetatable({}, mt)