Upgrade irssi to 1.4.2 and rebuild irssi-xmpp
https://irssi.org/2022/07/17/irssi-1.4.2-released/
irssi-xmpp has been patched (patches are from upstream's Github pull requests) to build without warnings, and the irssi command /load xmpp
also runs without errors.
Edited by rubicon