error message concerning enfold

Hi, I just chatted with my provider (one.com) to find the reason for an error message (see below).
When I changed the theme, the error message was gone and appeared again after reinstalling enfold and updating wordpress. The support assumed, that “it is possible that it does not work properly on updated wordpress site. So the theme developers needs to publish an update to fix the error.”
Can you help?
Warning: Creating default object from empty value in /customers/f/1/6/music-step-by-step.com/httpd.www/wp-content/themes/enfold/config-templatebuilder/avia-shortcodes/slideshow_layerslider/slideshow_layerslider.php on line 28 Warning: Cannot modify header information - headers already sent by (output started at /customers/f/1/6/music-step-by-step.com/httpd.www/wp-content/themes/enfold/config-templatebuilder/avia-shortcodes/slideshow_layerslider/slideshow_layerslider.php:28) in /customers/f/1/6/music-step-by-step.com/httpd.www/wp-includes/functions.php on line 6274 Warning: Cannot modify header information - headers already sent by (output started at /customers/f/1/6/music-step-by-step.com/httpd.www/wp-content/themes/enfold/config-templatebuilder/avia-shortcodes/slideshow_layerslider/slideshow_layerslider.php:28) in /customers/f/1/6/music-step-by-step.com/httpd.www/wp-admin/includes/misc.php on line 1310

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