Issue when dating next matches

Hi,
Hope somebody can help me. I got this issue when dating new matches in the championship mode.

PHP Warning: Invalid argument supplied for foreach() in D:\INETPUB\VHOSTS\ruidosdeporte.com\httpdocs\wp-content\plugins\leaguemanager\admin\show-league.php on line 24

https://ww.wp.xz.cn/plugins/leaguemanager/