Lua深层路径安全取值：多级字段的逐层兜底

-- 中间层缺失直接崩
local hp = cfg.map3.monster.hp

local function dig(root, keys, backup)
    local cur = root
    for i = 1, #keys do
        if type(cur) ~= "table" then
            return backup
        end
        cur = cur[keys[i]]
    end
    if cur == nil then return backup end
    return cur
end
local hp = dig(cfg, {"map3", "monster", "hp"}, 100)
local p = getplayerbyname("cfgwatch")
sendmsg(p, 1, "怪物血量兜底值 " .. hp)