How can the _checkCart function be improved to avoid returning incorrect results?

The issue with the _checkCart function returning incorrect results could be due to not properly validating the input data or not handling edge cases effectively. To improve the function, we can add additional checks to ensure that the input data is valid and handle any edge cases that may cause incorrect results.

function _checkCart($cart) {
    // Check if $cart is an array and not empty
    if (!is_array($cart) || empty($cart)) {
        return false;
    }
    
    // Add additional validation logic here if needed
    
    // Return true if all checks pass
    return true;
}