Not sure if this is helpful, but I just ran a PHP 7 Compatibility Checker and received these errors in reference to Send System Info:
FILE: /www/wp-content/plugins/send-system-info/views/output.php
-------------------------------------------------------------------------------------------------------------
FOUND 1 ERROR AND 1 WARNING AFFECTING 2 LINES
-------------------------------------------------------------------------------------------------------------
32 | ERROR | Extension 'mysql_' is deprecated since PHP 5.5 and removed since PHP 7.0; Use mysqli instead
39 | WARNING | INI directive 'safe_mode' is deprecated since PHP 5.3 and removed since PHP 5.4
-------------------------------------------------------------------------------------------------------------
FILE: /www/wp-content/plugins/send-system-info/includes/browser.php
----------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
----------------------------------------------------------------------------------------------
220 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
----------------------------------------------------------------------------------------------
Not sure if this is helpful, but I just ran a PHP 7 Compatibility Checker and received these errors in reference to Send System Info: