Ein Fehler vom Typ E_ERROR

Hello, I have this error and can’t edit my homepage:

WordPress-Version 5.8
Aktuelles Theme: Enfold Child (Version 1.0)
Aktuelles Plugin: (Version )
PHP-Version 7.1.33

Fehler-Details
==============
Ein Fehler vom Typ E_ERROR wurde in der Zeile 959 der Datei /home/herzber1/public_html/www.bernhardzemp.ch/wp-content/themes/enfold/config-templatebuilder/avia-shortcodes/slideshow_fullscreen/slideshow_fullscreen.php verursacht. Fehlermeldung: Uncaught Error: Call to undefined method avia_slideshow::default_args() in /home/herzber1/public_html/www.bernhardzemp.ch/wp-content/themes/enfold/config-templatebuilder/avia-shortcodes/slideshow_fullscreen/slideshow_fullscreen.php:959
Stack trace:
#0 /home/herzber1/public_html/www.bernhardzemp.ch/wp-content/themes/enfold/config-templatebuilder/avia-template-builder/php/class-shortcode-template.php(1107): avia_sc_slider_fullscreen->shortcode_handler(Array, ‘\n[av_full…’, ‘av_fullscreen’, Array)
#1 /home/herzber1/public_html/www.bernhardzemp.ch/wp-includes/shortcodes.php(356): aviaShortcodeTemplate->shortcode_handler_prepare(Array, ‘\n[av_full…’, ‘av_fullscreen’)
#2 [internal function]: do_shortcode_tag(Array)
#3 /home/herzber1/public_html/www.bernhardzemp.ch/wp-includes/shortcodes.php(228): preg_replace_callback(‘/\\[(\\[?)(av_but…’, ‘do_shortcode_ta…’, ‘[av_fullscreen …’)
#4 /home/herzber1/public_html/www.bernhardzemp.ch/wp-includes/class-wp-hook.php(303): do_shortcode(‘[av_fullscreen .