[Error] 
Non-static method Aim\LangHelper::isPageExists() cannot be called statically (0)
/home/bitrix/ext_www/ai-academy.ru/local/php_interface/classes/LangHelper.php:154
#0: Aim\LangHelper::getUrlForLang
	/home/bitrix/ext_www/ai-academy.ru/local/php_interface/classes/LangHelper.php:96
#1: Aim\LangHelper::getLangSwitchLink
	/home/bitrix/ext_www/ai-academy.ru/local/templates/ai-academy/header.php:156
#2: include_once(string)
	/home/bitrix/ext_www/ai-academy.ru/bitrix/modules/main/include/prolog_after.php:110
#3: require(string)
	/home/bitrix/ext_www/ai-academy.ru/bitrix/modules/main/include/prolog.php:11
#4: require_once(string)
	/home/bitrix/ext_www/ai-academy.ru/bitrix/header.php:1
#5: require(string)
	/home/bitrix/ext_www/ai-academy.ru/training/index.php:5
----------