Warning Messages Related to theme-plugin-activation.php line 1893

I’m seeing error messages in my dashboard, all regarding the file theme-plugin-activation.php line 1893, which appears to be an Aegaeus theme file.

All of the messages are basically the same. Here’s one of them (removed file path prior to /wp-content/):

Warning: Declaration of TGM_Bulk_Installer_Skin::before() should be compatible with Bulk_Upgrader_Skin::before($title = ”) in /..filepath../wp-content/themes/AegaeusWP/includes/theme-plugin-activation.php on line 1893

The googling I did suggested it’s a PHP error in the theme files. Please advise.

Thanks!