Eg if `$_GET['date']=today` is set, but `$_POST['date] = '';` then it might still trigger an exception like this otherwise:


> There was an error while regenerating container releases: Date format must be: YYYY-MM-DD, or 'today' or 'yesterday' or any keyword supported by the strtotime function (see http://php.net/strtotime for more information): #0 core/Date.php(148): Piwik\Date::getInvalidDateFormatException(false) #1 /core/Plugin/Controller.php(640): Piwik\Date::factory(false) #2 /core/Plugin/Controller.php(607): Piwik\Plugin\Controller->setGeneralVariablesViewAs(Object(Piwik\View), 'basic') #3 /plugins/TagManager/Controller.php(205): Piwik\Plugin\Controller->setGeneralVariablesView(Object(Piwik\View)) #4 /plugins/TagManager/Controller.php(53): Piwik\Plugins\TagManager\Controller->renderTemplate('@TagManager/deb...') #5 [internal function]: Piwik\Plugins\TagManager\Controller->debug() #6 /var/www/html/core/FrontController.php(590): call_user_func_array(Array, Array) #7 /core/FrontController.php
(165): Piwik\FrontController->doDispatch('TagManager', 'debug', Array) #8 plugins/TagManager/Context/WebContext/JavaScriptTagManagerLoader.php(72): Piwik\FrontController->dispatch('TagManager', 'debug') #9 /plugins/TagManager/Context/WebContext.php(166): Piwik\Plugins\TagManager\Context\WebContext\JavaScriptTagManagerLoader->getPreviewJsContent() #10