Fatal error: Uncaught Error: Call to undefined method WP_Theme_JSON::set_spacing_sizes() in /homepages/37/d915551013/htdocs/httpdocs/wp-content/plugins/gutenberg/lib/class-wp-theme-json-resolver-gutenberg.php:593 Stack trace: #0 /homepages/37/d915551013/htdocs/httpdocs/wp-content/plugins/gutenberg/lib/experimental/fonts-api/register-fonts-from-theme-json.php(14): WP_Theme_JSON_Resolver_Gutenberg::get_merged_data() #1 /homepages/37/d915551013/htdocs/httpdocs/wp-includes/class-wp-hook.php(307): gutenberg_register_fonts_from_theme_json('') #2 /homepages/37/d915551013/htdocs/httpdocs/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array) #3 /homepages/37/d915551013/htdocs/httpdocs/wp-includes/plugin.php(476): WP_Hook->do_action(Array) #4 /homepages/37/d915551013/htdocs/httpdocs/wp-settings.php(598): do_action('init') #5 /homepages/37/d915551013/htdocs/httpdocs/wp-config.php(97): require_once('/homepages/37/d...') #6 /homepages/37/d915551013/htdocs/httpdocs/wp-load.php(50): require_once('/homepages/37/d...') # in /homepages/37/d915551013/htdocs/httpdocs/wp-content/plugins/gutenberg/lib/class-wp-theme-json-resolver-gutenberg.php on line 593