Ignore "404" status pages with cURL - php

Question

I´m using cURL to get informations out of an API and write them in a MySQL table.
The url to the API looks like that:
https://eu.api.blizzard.com/data/wow/item-class/4/item-subclass/1?namespace=static-eu&locale=de_DE&access_token=US6XqgbtQ6rh3EVIqPsejuF62RwP8ljzWn
You can change the number from the url part 1?namespace to another value, for example to 4?namespace to get other informations from the API.
I´m using php "range" to generate the numbers for the url.
Problem:
Some numbers in the url leads to a 404 response, since there are no informations in the API. Example URL:
https://eu.api.blizzard.com/data/wow/item-class/4/item-subclass/18?namespace=static-eu&locale=de_DE&access_token=US6XqgbtQ6rh3EVIqPsejuF62RwP8ljzWn
These "404" pages should get ignored and nothing should be written in MySQL. How is this possible with cURL?
Complete code:
$ids = [];
foreach(range(0, 20) as $number) {
$ids[] = $number;
}
$userAgent = 'Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Firefox/31.0';
$mh = curl_multi_init();
$channels = [];
foreach ($ids as $id) {
$fetchURL = 'https://eu.api.blizzard.com/data/wow/item-class/4/item-subclass/' . $id . '?namespace=static-eu&locale=de_DE&access_token=US6XqgbtQ6rh3EVIqPsejuF62RwP8ljzWn';
$channels[$id] = curl_init($fetchURL);
curl_setopt($channels[$id], CURLOPT_RETURNTRANSFER, 1);
curl_setopt($channels[$id], CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($channels[$id], CURLOPT_SSL_VERIFYPEER, 0);
curl_multi_add_handle($mh, $channels[$id]);
}
// execute all queries simultaneously, and continue when all are complete
$running = null;
do {
curl_multi_exec($mh, $running);
curl_multi_select($mh);
} while ($running > 0);
//close the handles
foreach ($ids as $id) {
curl_multi_remove_handle($mh, $channels[$id]);
}
curl_multi_close($mh);
$response = [];
foreach($ids as $id){
$res = curl_multi_getcontent($channels[$id]);
$response[$id] = ($res === false) ? null : json_decode($res, true);
}
echo ("<pre>");
foreach ($response as $item) {
$sqle= "REPLACE INTO `itemsubclasses`
(`class_id`, `subclass`, `name`)
VALUES
('{$item['class_id']}', '{$item['subclass_id']}', '{$item['display_name']}')";
if ($conn->query($sqle) === TRUE) {
echo "Geklappt";
} else {
echo "Problem";
}
}