Segmentation fault (core dumped)

seg_fault.php

<?php
error_reporting(E_ALL);

require_once dirname(__FILE__) . '/../config/conf.inc.php';

//

        $cb = new Couchbase($couchbase['hosts'], $couchbase['user'], $couchbase['pass'], $couchbase['test_bucket']);
        $docs = array();
            for ($x = 1; $x <= 1000; $x++) {//$x = 1-1000
                $docs[]['TEST_DOC::' . $x] = '{"a" : 1}';
            }
            
            var_dump($cb->setMulti($docs));
            echo 'Returned: ' . $cb->getResultCode() . PHP_EOL;