Warning: Undefined array key "user" in /var/www/vhosts/impressie.online/httpdocs/wp-content/plugins/inschrijfmodule/inschrijfmodule.php on line 212

Fatal error: Uncaught TypeError: array_key_exists(): Argument #2 ($array) must be of type array, null given in /var/www/vhosts/impressie.online/httpdocs/wp-content/plugins/inschrijfmodule/inschrijfmodule.php:212
Stack trace:
#0 /var/www/vhosts/impressie.online/httpdocs/wp-includes/class-wp-hook.php(310): SignupModule->custom_redirects()
#1 /var/www/vhosts/impressie.online/httpdocs/wp-includes/class-wp-hook.php(334): WP_Hook->apply_filters()
#2 /var/www/vhosts/impressie.online/httpdocs/wp-includes/plugin.php(517): WP_Hook->do_action()
#3 /var/www/vhosts/impressie.online/httpdocs/wp-includes/template-loader.php(13): do_action()
#4 /var/www/vhosts/impressie.online/httpdocs/wp-blog-header.php(19): require_once('/var/www/vhosts...')
#5 /var/www/vhosts/impressie.online/httpdocs/index.php(17): require('/var/www/vhosts...')
#6 {main}
  thrown in /var/www/vhosts/impressie.online/httpdocs/wp-content/plugins/inschrijfmodule/inschrijfmodule.php on line 212