ElasticSearch PHP error 503 - php

Question

I'm quite new to ElasticSearch and just figuring some things out for now, but here is a problem. After all the trouble of changing the server we migrated the nodes, but have some missing data in one of them. We have two nodes that have records with the same ID in both of them. In 1'st one everything is ok, but in second some records seems to be missing. For example if I send the request like this:
GET /fnh_detailbeta/main/61UkVww8QGu093RirFG84A
I will get the following error (in Marvel - Sense)
{
"error": "NoShardAvailableActionException[[fnh_detailbeta][0] null]",
"status": 503
}
So, what I'm trying to do now is compare all the records in Node 1 with records in Node 2 via ElasticSearch PHP. Here is the PHP I'm trying to run:
<?php
require '../connector/vendor/autoload.php';
$number = 1;
$params = array();
$params['hosts'] = array (
'146.185.164.121:9200', // IP + Port
);
$client = new Elasticsearch\Client($params);
$getParams = array();
$getParams['index'] = 'fnh_mainbeta';
$getParams['type'] = 'main';
//REQUEST AMOUNT
$json = '{"query": {"match_all": {}},"size": 1,"from":'.$number.'}';
$getParams['body'] = $json;
$retDoc = $client->search($getParams);
$total = $retDoc['hits']['total'];
//END OF REQUEST AMOUNT
//REQUEST ID
for ($i = 1; $i <= $total; $i++) {
$json = '{"query": {"match_all": {}},"size": 1,"from":'.$number.'}';
$getParams = array();
$getParams['index'] = 'fnh_mainbeta';
$getParams['type'] = 'main';
$getParams['body'] = $json;
$getParams['ignore'] = 503;
$getParams['ignore'] = 404;
$retDoc = $client->search($getParams);
$found_id = $retDoc['hits']['hits'][0]['_id'];
echo $found_id;
//REGUEST SECOND DB
$getParams = array();
$getParams['index'] = 'fnh_detailbeta';
$getParams['type'] = 'main';
$getParams['id'] = '61UkVww8QGu093RirFG84A';
$retDoc = $client->get($getParams);
$found_id_two = $retDoc['_id'];
echo $found_id_two;
//END OF REQUEST SECOND DB
$number++;
sleep(1);
};
//END OF REQUEST AMOUNT
It is not finished by now, but I get the fatal error that exits the script:
Fatal error: Uncaught exception 'Guzzle\Http\Exception\ServerErrorResponseException' with message 'Server error response
[status code] 503
[reason phrase] Service Unavailable
This error appears when NoShardAvailableActionException[[fnh_detailbeta][0] null]... So, the question is:
What is the best way to catch this error (something like IF error THEN echo "error") without stop of the PHP execution. In other words - I want to determine this error, delete this record and go further comparing the Nodes.
Any help will be appreciated!