999. The debtor is placed in default either by the terms of the contract, through the lapse of the time specified for its performance; or by the mere operation of law; or by the commencement of a suit, or by a demand which must be in writing except in the case of a verbal contract.
1000. The debtor is also in default, when the thing which he or she has bound himself or herself to give or to do could only have been given or done within a time which he or she has allowed to expire.