GLOBALS:

Array
(
    [_GET] => Array
        (
            [route] => courses/php7-i-mysql-sredniy-uroven/урок-4/ubuntu-postfix-dovecot-squirrelmail
            [_module] => courses
            [_page] => lesson
            [key] => php7-i-mysql-sredniy-uroven
            [id] => урок-4
            [title] => ubuntu-postfix-dovecot-squirrelmail
        )

    [_POST] => Array
        (
        )

    [_COOKIE] => Array
        (
        )

    [_FILES] => Array
        (
        )

    [_SERVER] => Array
        (
            [USER] => www-data
            [HOME] => /var/www
            [HTTP_CDN_LOOP] => cloudflare
            [HTTP_CF_CONNECTING_IP] => 18.207.129.133
            [HTTP_IF_MODIFIED_SINCE] => Thu, 22 Apr 2021 17:35:45 GMT
            [HTTP_ACCEPT_LANGUAGE] => en-US,en;q=0.5
            [HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
            [HTTP_USER_AGENT] => CCBot/2.0 (https://commoncrawl.org/faq/)
            [HTTP_CF_VISITOR] => {"scheme":"https"}
            [HTTP_X_FORWARDED_PROTO] => https
            [HTTP_CF_RAY] => 673ffa57b84457f7-IAD
            [HTTP_X_FORWARDED_FOR] => 18.207.129.133
            [HTTP_CF_IPCOUNTRY] => US
            [HTTP_ACCEPT_ENCODING] => gzip
            [HTTP_CONNECTION] => Keep-Alive
            [HTTP_HOST] => school-php.com
            [REDIRECT_STATUS] => 200
            [SERVER_NAME] => school-php.com
            [SERVER_PORT] => 443
            [SERVER_ADDR] => 178.57.218.141
            [REMOTE_USER] => 
            [REMOTE_PORT] => 50826
            [REMOTE_ADDR] => 172.69.63.22
            [SERVER_SOFTWARE] => nginx/1.18.0
            [GATEWAY_INTERFACE] => CGI/1.1
            [HTTPS] => on
            [REQUEST_SCHEME] => https
            [SERVER_PROTOCOL] => HTTP/1.1
            [DOCUMENT_ROOT] => /var/www/school-php.com
            [DOCUMENT_URI] => /index.php
            [REQUEST_URI] => /courses/php7-i-mysql-sredniy-uroven/%D1%83%D1%80%D0%BE%D0%BA-4/ubuntu-postfix-dovecot-squirrelmail
            [SCRIPT_NAME] => /index.php
            [CONTENT_LENGTH] => 
            [CONTENT_TYPE] => 
            [REQUEST_METHOD] => GET
            [QUERY_STRING] => route=courses/php7-i-mysql-sredniy-uroven/%D1%83%D1%80%D0%BE%D0%BA-4/ubuntu-postfix-dovecot-squirrelmail
            [SCRIPT_FILENAME] => /var/www/school-php.com/index.php
            [PATH_INFO] => 
            [FCGI_ROLE] => RESPONDER
            [PHP_SELF] => /index.php
            [REQUEST_TIME_FLOAT] => 1627159376.9011
            [REQUEST_TIME] => 1627159376
        )

    [t] => 1627159376.9018
    [GLOBALS] => Array
 *RECURSION*
    [_SESSION] => Array
        (
            [antixsrf] => 449592ebcfb8e87f52ab2c8cafa4f5e1
        )

)

DEBUG BACKTRACE

#0  FW\MyErrorHandler\MyErrorHandler::handler(2, Trying to access array offset on value of type null, /var/www/school-php.com/modules/courses/lesson.php, 295) called at [/var/www/school-php.com/modules/courses/lesson.php:295]
#1  require(/var/www/school-php.com/modules/courses/lesson.php) called at [/var/www/school-php.com/modules/courses/controller/controller.php:11]
#2  require(/var/www/school-php.com/modules/courses/controller/controller.php) called at [/var/www/school-php.com/index.php:221]
#3  FrontController::init(courses/php7-i-mysql-sredniy-uroven/урок-4/ubuntu-postfix-dovecot-squirrelmail) called at [/var/www/school-php.com/index.php:251]

TIPS

Незадокументированный тип ошибки