Thread:Extension talk:Semantic Extra Special Properties/Undefined variable: firstAuthor

Hi. I'm running SESP version 0.2.8 alpha and when I run runJobs.php I'm getting the following error: Notice: Undefined variable: firstAuthor in /var/www/webapps/wiki/extensions/Semantic-Extra-Special-Properties/SemanticExtraSpecialProperties.hooks.php on line 255 Initialisation value '' is not a number. Backtrace: I guess this is a bug?
 * 1) 0 /var/www/webapps/wiki/extensions/Semantic-Extra-Special-Properties/SemanticExtraSpecialProperties.hooks.php(276): SMWDINumber->__construct(NULL)
 * 2) 1 [internal function]: SemanticESP::sespUpdateDataBefore(Object(SMWSQLStore3), Object(SMWSemanticData))
 * 3) 2 /var/www/webapps/wiki/includes/Hooks.php(216): call_user_func_array('SemanticESP::se...', Array)
 * 4) 3 /var/www/webapps/wiki/includes/GlobalFunctions.php(3856): Hooks::run('SMWStore::updat...', Array)
 * 5) 4 /var/www/webapps/wiki/extensions/SemanticMediaWiki/includes/storage/SMW_Store.php(216): wfRunHooks('SMWStore::updat...', Array)
 * 6) 5 /var/www/webapps/wiki/extensions/SemanticMediaWiki/includes/SMW_ParseData.php(374): SMWStore->updateData(Object(SMWSemanticData))
 * 7) 6 /var/www/webapps/wiki/extensions/SemanticMediaWiki/includes/SMW_ParseData.php(518): SMWParseData::storeData(Object(ParserOutput), Object(Title), true)
 * 8) 7 [internal function]: SMWParseData::onLinksUpdateConstructed(Object(LinksUpdate))
 * 9) 8 /var/www/webapps/wiki/includes/Hooks.php(216): call_user_func_array('SMWParseData::o...', Array)
 * 10) 9 /var/www/webapps/wiki/includes/GlobalFunctions.php(3856): Hooks::run('LinksUpdateCons...', Array)
 * 11) 10 /var/www/webapps/wiki/includes/LinksUpdate.php(99): wfRunHooks('LinksUpdateCons...', Array)
 * 12) 11 /var/www/webapps/wiki/includes/job/RefreshLinksJob.php(49): LinksUpdate->__construct(Object(Title), Object(ParserOutput), false)
 * 13) 12 /var/www/webapps/wiki/maintenance/runJobs.php(80): RefreshLinksJob->run
 * 14) 13 /var/www/webapps/wiki/maintenance/doMaintenance.php(105): RunJobs->execute
 * 15) 14 /var/www/webapps/wiki/maintenance/runJobs.php(110): require_once('/var/www/webapp...')
 * 16) 15 {main}

Thanks