MagpieRSS::feed_start_element() error with PHP 8.0 and 8.1

[andrewcsp]

Bug report

Summary

I've noticed the following error appears hundreds of times related to MagpieRSS when running PHP 8.0 or 8.1

(ERROR @ /home/user/core/model/modx/xmlrss/magpierss.class.php : 133) PHP warning: MagpieRSS::feed_start_element(): Argument #3 ($attrs) must be passed by reference, value given

Step to reproduce

To reliably reproduce the Magpie errors, delete the contents of your cache folder (within core), then load the MODX manager homepage/dashboard (i.e. domain.com/manager/)

Observed behavior

Review the errors in Manage > Reports > Error Log. You should see hundreds of the above MagpieRSS error (186 of them for me).

Expected behavior

I would expect to see no MagpieRSS errors.

Environment

MODX Revolution 2.8.4-pl Apache/2.4.53 (cPanel) 10.3.35-MariaDB Confirmed with PHP Version 8.0.19 and 8.1.6. The problem does not occur with PHP 7.4.29.