Same here. It’s just a standard PHP notice due to an uninitialized array value being incremented. Nothing to worry about (other than an error message on your page) but you can fix it like this:
if ( $new !== false ) {
// RP - initialize array value to avoid PHP notice.
if (!isset($new_count[$new])) {
$new_count[$new] = 0;
};
$new_count[$new]++;
}