javascript - Uncaught TypeError: Can not read property 'odd' of undefined

Hello

In my JavaScript code I get the following error:

  

"Uncaught TypeError: Can not read property 'odd' of undefined"

Since I'm new to the area, I do not understand how to solve the problem, can you help me?

case 'multiple_2_3':

    total = 3 * self.card.quantity;
    $("#resume-odds").hide();
    //gains = (cota1 * cota2) * self.card.quantity + (cota1 * cota3) * self.card.quantity +  (cota2 * cota3) * self.card.quantity
    for (let i in self.card.bets) {
        let bet1 = self.card.bets[i];
        if(self.card.bets.length > i){
        for (let j = i + 1; j < self.card.bets.length; j++) {
            let bet2 = self.card.bets[j];
            gains += parseFloat(bet1.odd) * parseFloat(bet2.odd) * self.card.quantity;
        }
        }
    }

    break;
case 'multiple_2_4':
    total = 6 * self.card.quantity;
    $("#resume-odds").hide();

    for (let i in self.card.bets) {
        let bet1 = self.card.bets[i];
        for (let j = i + 1; j < self.card.bets.length; j++) {
            let bet2 = self.card.bets[j];
            gains += parseFloat(bet1.odd) * parseFloat(bet2.odd) * self.card.quantity;
        }
    }

    break;