WikiTextStructure uses the cirrussearch-ignored-headings i18n message from CirrusSearch, which won't exist if the extension isn't installed
/** * Gets a list of heading to ignore. * @return string[] */ private function getIgnoredHeadings() { static $ignoredHeadings = null; if ( $ignoredHeadings === null ) { $ignoredHeadings = []; $source = wfMessage( 'search-ignored-headings' )->inContentLanguage(); if ( $source->isBlank() ) { // Try the old version too, just in case $source = wfMessage( 'cirrussearch-ignored-headings' )->inContentLanguage(); } if ( !$source->isDisabled() ) { $lines = self::parseSettingsInMessage( $source->plain() ); // Now we just have headings! $ignoredHeadings = $lines; } } return $ignoredHeadings; }
I suspect we can just remove that "fallback...