Oh no! Something irrecoverable has happened...
app\exceptions\OutputException (Code: 0) thrown in /usr/local/submitty/site/app/libraries/Output.php (Line 412) by:
            throw new OutputException("{$e->getMessage()} in {$e->getFile()}:{$e->getLine()}");
Message:
An exception has been thrown during the rendering of a template ("app\models\gradeable\Gradeable::getTeamLockDate(): Return value must be of type DateTime, null returned") in "admin/admin_gradeable/AdminGradeableDates.twig" at line 14. in /usr/local/submitty/site/app/templates/admin/admin_gradeable/AdminGradeableDates.twig:14
Stack Trace:
#0 /usr/local/submitty/site/app/libraries/Output.php(425): app\libraries\Output->renderTwigTemplate()
#1 /usr/local/submitty/site/app/controllers/admin/AdminGradeableController.php(617): app\libraries\Output->renderTwigOutput()
#2 /usr/local/submitty/site/app/controllers/admin/AdminGradeableController.php(32): app\controllers\admin\AdminGradeableController->editPage()
#3 unknown file(unknown line): app\controllers\admin\AdminGradeableController->editGradeableRequest()
#4 /usr/local/submitty/site/app/libraries/routers/WebRouter.php(254): call_user_func_array()
#5 /usr/local/submitty/site/app/libraries/routers/WebRouter.php(232): app\libraries\routers\WebRouter->run()
#6 /usr/local/submitty/site/public/index.php(147): app\libraries\routers\WebRouter::getWebResponse()
USER: instructor