Lua循环边界：差一错误的三处高发点

local function sum(t)
    local s = 0
    for i = 1, #t - 1 do            -- 少算末位，差一
        s = s + t[i]
    end
    return s
end

local function sum(t)
    local s = 0
    for i = 1, #t do                -- 全量含末位
        s = s + t[i]
    end
    return s
end
sendmsg(actor, 1, "背包数量合计 "
    .. sum({10, 20, 30, 40}) .. " / 共4格")