If an article isn't assigned to a journal issue, the year tag inside may be used to indicate that the article is in press, which causes a fatal error from the CiteProc:
PHP Fatal error: Uncaught Seboettg\CiteProc\Exception\InvalidDateTimeException: Could not create valid date with year=in press, month=1, day=1. in /home/doc/OJS/development/e-med/ojs/plugins/generic/jatsParser/JATSParser/vendor/seboettg/citeproc-php/src/Rendering/Date/DateTime.php:45
If an article isn't assigned to a journal issue, the
year
tag inside may be used to indicate that the article is in press, which causes a fatal error from the CiteProc: