[Plugin: LeagueManager] New Version (2.9) Breaks Website

After installing or trying to update League Manager, my website and my admin pages give the following error 5 times at the top above the normal display of the page:

Warning: Missing argument 1 for leaguemanager() in /homepages/43/d201807468/htdocs/PatriettesWP/wp-content/plugins/leaguemanager/lib/core.php on line 83

Version 2.8 worked OK.

Since I’m on a deadline and have to move on for now, I’m going to uninstall the plugin. However, since LeagueManager is the best tool for what I’m trying to do, I’d like to see if there is a resolution.