TYPO3 Core

I can acknowledge this one, someone planed it to resolve this problem?

The problem is that in the $tabParts array.
The script is trying to access $sheetCfg as an array and this is of course only a String ... it is at line ~ 2198

Original:
//-----------------

// Add to tab:
$tabParts[] = array(
'label' => ($sheetCfg['ROOT']['TCEforms']['sheetTitle'] ? $this->sL($sheetCfg['ROOT']['TCEforms']['sheetTitle']) : $sheet),
'description' => ($sheetCfg['ROOT']['TCEforms']['sheetDescription'] ? $this->sL($sheetCfg['ROOT']['TCEforms']['sheetDescription']) : ''),
'linkTitle' => ($sheetCfg['ROOT']['TCEforms']['sheetShortDescr'] ? $this->sL($sheetCfg['ROOT']['TCEforms']['sheetShortDescr']) : ''),
'content' => $sheetContent
);

You can solve this by adding this only a check and a copy:

// new line:
//---------------
if (!is_array($sheetCfg)) $sheetCfg = $dataStruct; // if is not an array, so except to copy the included array from file

// Add to tab:
$tabParts[] = array(
'label' => ($sheetCfg['ROOT']['TCEforms']['sheetTitle'] ? $this->sL($sheetCfg['ROOT']['TCEforms']['sheetTitle']) : $sheet),
'description' => ($sheetCfg['ROOT']['TCEforms']['sheetDescription'] ? $this->sL($sheetCfg['ROOT']['TCEforms']['sheetDescription']) : ''),
'linkTitle' => ($sheetCfg['ROOT']['TCEforms']['sheetShortDescr'] ? $this->sL($sheetCfg['ROOT']['TCEforms']['sheetShortDescr']) : ''),
'content' => $sheetContent
);

This bug should be a "bug" or "crash" and not "feature" - its obviously supposed to be working :)

And 4.1.4