Why is this giving me an error?

for(let i=0;jobCard.length;i++){
            if(jobCard[i].classList.contains('hidden')) {
                jobCard[i].classList.remove('hidden');
            }
        }

for(let i=0;jobCard.length;i++){
            if(jobCard[i].classList.contains('hidden')) {
                jobCard[i].classList.remove('hidden');
            }
        }