Description:
------------
Failed to parse solr response on 500 responses from Solr Server using JSON or PHPS response writer.
Throwing SolrClientException with raw response instead of SolrServerException

Test script:
---------------
require_once "bootstrap.inc";
$options = array
(
        'hostname' => SOLR_SERVER_HOSTNAME,
        'login'    => SOLR_SERVER_USERNAME,
        'password' => SOLR_SERVER_PASSWORD,
        'port'     => SOLR_SERVER_PORT,
        'path'     => SOLR_SERVER_PATH,
        'wt'       => 'json'
);

$client = new SolrClient($options);

$query = new SolrQuery('*:*');

$func = new SolrCollapseFunction('manu_id_s');

$func->setMax('sum(cscore(),field(manu_id_s))');
$func->setSize(100);
$func->setNullPolicy(SolrCollapseFunction::NULLPOLICY_EXPAND);

$query->collapse($func);
try {
    $queryResponse = $client->query($query);
} catch (SolrServerException $e) {
    printf("Exception code %d", $e->getCode());
    assert(strlen($e->getMessage()) > 0, 'Exception message is empty');
}

Expected result:
----------------
Exception code 500

Actual result:
--------------
Notice: SolrClient::query(): Unable to find message in error response zval
Uncaught SolrClientException with raw response