Lua script to check if Lua registry is corrupted

check-registry.lua

function check_registry()
    local reg = debug.getregistry()
    local s, cur, min, max = #reg + 1, 0
    local ids, lst = {}, {n = 0}
    while type(reg[cur]) == "number" do
        if ids[cur] then return false, (table.concat(lst, "-")..": cycle "..cur) end
        ids[cur] = 1
        lst.n = lst.n + 1
        lst[lst.n] = cur
        if lst.n == 1 then
            min = reg[cur]
            max = reg[cur]
        else
            if cur < min then min = cur end
            if cur > max then max = cur end
        end
        cur = reg[cur]
    end
    local path = table.concat(lst, "-").."#"..cur
    if reg[cur] == nil then
        if cur ~= s then return false, (path..": nil end at "..cur.." instead of "..s)
        else
            if min and max then
                for i = min, max do
                    if type(reg[i]) == "number" then
                        local id = ids[reg[i]]
                        if id then
                            if id < 1 then return false, (path..": duplicate int "..reg[i].." within "..min.."-"..max) end
                            ids[reg[i]] = id - 1
                        end
                    end
                end
            end
            return true, path
        end
    else
        return false, (path..": value of type "..type(reg[cur]).." at "..cur.." instead of number or last-nil")
    end
end