GovnoCode

<?php

class Curl
{
    protected static $userAgent = 'Mozilla/5.0 (Linux; Android 6.0.1; SM-G532F Build/MMB29T) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.103 YaBrowser/18.7.1.575.00 Mobile Safari/537.36';
    protected static $arrParams = [
        'error' => false,
        'headers' => false,
        'user_agent' => null,
    ];

    public function __construct ($arrParams = [])
    {
        $this->params = (object) array_merge(self::$arrParams, $arrParams);

        if (empty ($this->params->user_agent)) $this->params->user_agent = self::$userAgent;
    }

var_dump($this->params); // ошибочка