Why does my code get stuck in this if statement?

This is a solution I wrote on leetcode to find the maximum profit in an array. When I submit it will give me a runtime error. After spending some time debugging, I found my code gets stuck in the if statement pointed out below. I can't seem to find any incorrect syntax use. So where did I do wrong?

int maxProfit(vector<int>& prices) {
    int profit=0;
    for(int i=0; i<prices.size()-1; i++){
        if(prices[i+1] > prices[i]){   // <--stuck here;
            profit += (prices[i+1] - prices[i]);
        }
    }
    return profit;
}