Calling assert function with first argument as string ist deprecated in PHP 7.2

There is a PHP 7.2 in this module. You get the following PHP notice messages:

Deprecated function: assert(): Calling assert() with a string argument is deprecated in Drupal\field_permissions\Plugin\FieldPermissionType\CustomAccess->hasFieldAccess() (Zeile 31 in /var/www/drupal/web/modules/contrib/field_permissions/src/Plugin/FieldPermissionType/CustomAccess.php)

Calling the first argument of the function as string is deprecated since PHP 7.2, so the string should be removed (https://secure.php.net/manual/de/function.assert.php).