TYPO3 Core

Thank you, Jose for input! It seems that the same js error exists in version 6.1 too and it doesn't make harm.

So I went to bit different direction, and it seems that ajax that supposes to give json array with list of content elements and pages gives quite poor set (typo3/ajax.php?ajaxID=ExtDirect::route&namespace=TYPO3.Workspaces). This array is returned by \TYPO3\CMS\Workspaces\ExtDirect\ActionHandler::loadColumnModel and it is taken from (if it's in workspace with number 1) global: $GLOBALS['BE_USER']->uc['moduleData']['Workspaces']['1']['columns'];

Now, I have no idea why this set is so poor.

still an issue in both 6.2.15 and 7.5-dev (latest master)

Patch set 1 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/44306

Patch set 1 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/44307

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/44307