And it indeed only occurs when Divi is enabled.
Hopefully they will fix it 
Full stack trace for reference:
ArgumentCountError: Uncaught exception 'ArgumentCountError' with message 'Too few arguments to function ET_GB_Block_Layout::get_the_excerpt(), 1 passed in /www/sociocracyforall_679/public/wp-includes/class-wp-hook.php on line 303 and exactly 2 expected' in /www/sociocracyforall_679/public/wp-content/themes/Divi/includes/builder/feature/gutenberg/blocks/Layout.php:207
in ET_GB_Block_Layout::get_the_excerpt called at /www/sociocracyforall_679/public/wp-includes/class-wp-hook.php (303)
in WP_Hook::apply_filters called at /www/sociocracyforall_679/public/wp-includes/plugin.php (189)
in apply_filters called at /www/sociocracyforall_679/public/wp-content/plugins/wp-discourse/lib/discourse-publish.php (271)
in WPDiscourse\DiscoursePublish\DiscoursePublish::sync_to_discourse_work called at /www/sociocracyforall_679/public/wp-content/plugins/wp-discourse/lib/discourse-publish.php (209)
in WPDiscourse\DiscoursePublish\DiscoursePublish::sync_to_discourse called at /www/sociocracyforall_679/public/wp-content/plugins/wp-discourse/lib/discourse-publish.php (158)
in WPDiscourse\DiscoursePublish\DiscoursePublish::publish_post_after_save called at /www/sociocracyforall_679/public/wp-includes/class-wp-hook.php (305)
in WP_Hook::apply_filters called at /www/sociocracyforall_679/public/wp-includes/class-wp-hook.php (327)
in WP_Hook::do_action called at /www/sociocracyforall_679/public/wp-includes/plugin.php (470)
in do_action called at /www/sociocracyforall_679/public/wp-includes/post.php (5180)
in wp_after_insert_post called at /www/sociocracyforall_679/public/wp-includes/post.php (4482)
in wp_insert_post called at /www/sociocracyforall_679/public/wp-includes/post.php (4570)
in wp_update_post called at /www/sociocracyforall_679/public/wp-admin/includes/post.php (423)
in edit_post called at /www/sociocracyforall_679/public/wp-admin/post.php (227)