TYPO3 Core

When providing an empty string (for example because the label was not yet added to the locallang file) as header in a wizard item, opening the new content element wizard throws an exception.

This occurs because the method prepareContent() in \TYPO3\CMS\Backend\Controller\ContentElement\NewContentElementController uses if ($wInfo['header']) { as condition instead of e.g. if (isset($wInfo['header'])) {.
It's not a big issue, it just seems wrong because in the if block it specifically uses a fallback in case the header is empty, which currently will never be used because of the if condition.