Fatal Error when trying to activate

The full stack trace from the log (with IP and web address aliased to anonymous):

PHP Fatal error:  Uncaught exception 'LogicException' with message 'Illegal value passed (no array or string given)' in /www/website.com/wp-content/plugins/wp-mail-smtp/wp-mail-smtp.php:58, referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0] Stack trace:, referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0] #0 /www/website.com/wp-content/plugins/wp-mail-smtp/wp-mail-smtp.php(58): spl_autoload_register(NULL), referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0] #1 /www/website.com/wp-content/plugins/wp-mail-smtp/wp_mail_smtp.php(52): require_once('/www/website....'), referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0] #2 /www/website.com/wp-admin/includes/plugin.php(1897): include('/www/website....'), referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0] #3 /www/website.com/wp-admin/plugins.php(172): plugin_sandbox_scrape('wp-mail-smtp/wp...'), referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0] #4 {main}, referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26
[Tue Feb 13 17:28:08 2018] [error] [client 0.0.0.0]   thrown in /www/website.com/wp-content/plugins/wp-mail-smtp/wp-mail-smtp.php on line 58, referer: http://www.website.com/wp-admin/plugins.php?error=true&plugin=wp-mail-smtp%2Fwp_mail_smtp.php&_error_nonce=6d70143a26