Heey people,
The author is not responding unfortunately but I fixed this by adding a check on the variable.
Go to the file wp-content/plugins/weekly-class-schedule/includes/wcs3_css.php
Search for (line 13):
$heading_text = $wcs3_options['color_heading_text'];
and replace that with:
$heading_text = '';
if(isset($wcs3_options['color_heading_text'])){ $heading_text = $wcs3_options['color_heading_text']; }
Good luck!
