PHP Fatal error:  Uncaught TypeError: implode(): Argument #1 ($pieces) must be of type array, string given in /var/www/html/vendor/symfony/http-client/Response/TransportResponseTrait.php:129

<?php

use Symfony\Component\HttpClient\HttpClient;

require_once __DIR__.'/vendor/autoload_runtime.php';

$client = HttpClient::create();

$client->request('GET', 'http://flyshooting-ios.casual.g.mi.com/.env.bak', ['timeout' => 5])->getContent();

PHP Warning:  Undefined array key "url" in /var/www/html/vendor/symfony/http-client/Response/TransportResponseTrait.php on line 129
PHP Warning:  curl_multi_exec(): Could not call the CURLOPT_HEADERFUNCTION in /var/www/html/vendor/symfony/http-client/Response/CurlResponse.php on line 302
PHP Fatal error:  Uncaught TypeError: implode(): Argument #1 ($pieces) must be of type array, string given in /var/www/html/vendor/symfony/http-client/Response/TransportResponseTrait.php:129
Stack trace:
#0 /var/www/html/vendor/symfony/http-client/Response/TransportResponseTrait.php(129): implode('', NULL)
#1 /var/www/html/vendor/symfony/http-client/Response/CurlResponse.php(379): Symfony\Component\HttpClient\Response\CurlResponse::addResponseHeaders(Array, Array, Array)
#2 /var/www/html/vendor/symfony/http-client/Response/CurlResponse.php(88): Symfony\Component\HttpClient\Response\CurlResponse::parseHeaderLine(Object(CurlHandle), 'HTTP/1.1 000 ', Array, Array, Array, Object(Symfony\Component\HttpClient\Internal\CurlClientState), 9, NULL, Object(Closure), NULL)
#3 [internal function]: Symfony\Component\HttpClient\Response\CurlResponse::Symfony\Component\HttpClient\Response\{closure}(Object(CurlHandle), 'HTTP/1.1 000 ')
#4 /var/www/html/vendor/symfony/http-client/Response/CurlResponse.php(302): curl_multi_exec(Object(CurlMultiHandle), 0)
#5 /var/www/html/vendor/symfony/http-client/Response/TransportResponseTrait.php(178): Symfony\Component\HttpClient\Response\CurlResponse::perform(Object(Symfony\Component\HttpClient\Internal\CurlClientState), Array)
#6 /var/www/html/vendor/symfony/http-client/Response/CommonResponseTrait.php(149): Symfony\Component\HttpClient\Response\CurlResponse::stream(Array, NULL)
#7 /var/www/html/vendor/symfony/http-client/Response/CommonResponseTrait.php(44): Symfony\Component\HttpClient\Response\CurlResponse::initialize(Object(Symfony\Component\HttpClient\Response\CurlResponse))
#8 /var/www/html/vendor/symfony/http-client/Response/CurlResponse.php(244): Symfony\Component\HttpClient\Response\CurlResponse->doGetContent(true)
#9 /var/www/html/test.php(12): Symfony\Component\HttpClient\Response\CurlResponse->getContent()
#10 /var/www/html/vendor/autoload_runtime.php(9): require('/var/www/html/t...')
#11 /var/www/html/test.php(7): require_once('/var/www/html/v...')
#12 {main}
  thrown in /var/www/html/vendor/symfony/http-client/Response/TransportResponseTrait.php on line 129

$ curl -vvv http://flyshooting-ios.casual.g.mi.com/.env.bak
*   Trying 20.47.97.231:80...
* Connected to flyshooting-ios.casual.g.mi.com (20.47.97.231) port 80 (#0)
> GET /.env.bak HTTP/1.1
> Host: flyshooting-ios.casual.g.mi.com
> User-Agent: curl/7.74.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 000 
< Date: Tue, 14 Dec 2021 14:12:58 GMT
< Content-Type: text/html
< Content-Length: 0
< Connection: keep-alive
< Server: MonKing/3.14
< Xiaomi-Security-Center: if any vulnerability found, go https://sec.xiaomi.com
< 
* Connection #0 to host flyshooting-ios.casual.g.mi.com left intact