LUA|MTASA 的 attempt to index field '?' (a nil value) 问题

我在我的 MTA 服务器的 lua 脚本中遇到了问题。当我运行代码时，我会得到以下错误：

attempt to index field '?' (a nil value)

这是代码：

addEvent("bank:transfer", true)
addEventHandler("bank:transfer", root, function(id, amount, to, reason)
    if(transferBank(id, amount, to, reason)) then
         triggerClientEvent(client, "bank:transferRecieve", client, true)
    else
         triggerClientEvent(client, "bank:transferRecieve", client, false)
    end
end)

function transferBank(id, amount, to, reason)
    if(id and amount and to and reason) then
        if(BANK_ACCOUNTS[to]) then
            if(BANK_ACCOUNTS[id].balance >= amount) then
                dbExec(connection, "INSERT INTO bank_records (bank_id, record_type, record_from, reason, amount, date) VALUES(?, ?, ?, ?, ?, NOW())", to, 3, id, reason, amount)
                dbExec(connection, "UPDATE bank_accounts SET balance = balance - ? WHERE id=?", amount, id)
                dbExec(connection, "UPDATE bank_accounts SET balance = balance + ? WHERE id=?", amount, to)
                BANK_ACCOUNTS[to].balance = BANK_ACCOUNTS[to].balance + amount
                BANK_ACCOUNTS[id].balance = BANK_ACCOUNTS[id].balance - amount

                return true
            else
                return false, "Le Compte Bancaire spécifié ne contient pas assez d'argent."
            end
        else
            return false, "Le Compte Bancaire spécifié n'existe pas."
        end
    else
        return false, "Argument Invalide."
    end
end

我搜索了几个小时，但我找不到错误来自哪里的原因。