Paid items required is checked but customers were still able to checkout with only a reward item:

The reason this can happen is that once LoyaltyLion has loaded onto the page we run some checks to assert that the cart doesn't contain any invalid items. If detected, we remove those items with the Shopify Ajax API. However, none of that is instant. It is usually pretty fast but if:

 1. Customer has a paid item in cart
 2. Customer redeems a free product reward
 3. On the cart page, customer removes the paid item
 4. Customer then very quickly navigates to checkout before LL has loaded

We wouldn't have a chance to identify and remove the reward item before page navigates away to checkout. It's unfortunately a Shopify limitation at this time and we can't do more to guard against it without negatively impacting checkout flow. 

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