Fatal error: Uncaught Error: Call to a member function getId() on null in /mnt/data177/www/html/jurnal/lib/pkp/classes/publication/PKPPublication.inc.php:149 Stack trace: #0 /mnt/data177/www/html/jurnal/lib/pkp/classes/submission/PKPSubmission.inc.php(423): PKPPublication->getAuthorString() #1 /mnt/data177/www/html/jurnal/cache/t_compile/00a0a0910209607cb33eb0fe6474f30ed7399ed7^7cf1cd52b8ba8108de77f197078de34b733dd394_0.app.frontendobjectsarticle_summary.tpl.php(77): PKPSubmission->getAuthorString() #2 /mnt/data177/www/html/jurnal/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_resource_base.php(123): content_65f27b4fa6c932_05853634() #3 /mnt/data177/www/html/jurnal/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_template_compiled.php(114): Smarty_Template_Resource_Base->getRenderedTemplateCode() #4 /mnt/data177/www/html/jurnal/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_template.php(217): Smarty_Template_Compiled->render() #5 /mnt/data177/www/html/jurnal/lib/pkp/lib/vendor/sm in /mnt/data177/www/html/jurnal/lib/pkp/classes/publication/PKPPublication.inc.php on line 149