Fatal Error: PHP error

Discussion options page displays an error and breaks the rest of the options page on the bottom of page.

Default Avatar
For users without a custom avatar of their own, you can either display a generic logo or a generated one based on their e-mail address.

Fatal error: Call to undefined function get_user_id_from_string() in /home/noxmcpvp/public_html/wp-content/plugins/minepic/minepic.php on line 125

Same exact issue as https://wordpress.org/support/topic/fatal-error-1139?replies=3#post-5448442

However this issue has not been fixed.

https://wordpress.org/plugins/minepic/