Lua安全取值：深层路径的逐层校验

-- 错误：一行到底，断一层就崩
local gold = cfg.activity.reward.gold

local function safeGet(t, path, default)
    local cur = t
    for key in string.gmatch(path, "[^%.]+") do
        if type(cur) ~= "table" then
            return default
        end
        cur = cur[key]
    end
    if cur == nil then return default end
    return cur
end
local gold = safeGet(cfg, "activity.reward.gold", 0)
local p = getplayerbyname("safe01")
sendmsg(p, 1, "gold=" .. gold)