TYPO3 Core

It seems to be a combination of an unlucky extension programming:
$this->data is empty, instead everything is in $this->cObj->data.

But I can't find the part where changed this( kickstarter generated extension).

But i think it should still get caught by tslib_content in any case.

I did again more investigations:
in pibase->pi_getEditpanel a temporay CObject is created. If either the first ($row ) or the second argument ($tablename) evaluate to false, they are initialised from $this->internal['currentRow']; and
$this->internal['currentTable'];

If used with 2 empty strings as dummy arguments, and these fallback values are not set as array() and string, then the error occurs.

Possible fixes: In the extension use:
$this->pi_getEditPanel(array(''),'<table name>','',$econf));

In core:
1.
pi_base->pi_getEditPanel()
check the validity of the fallbacks as well and supply useful defaults.
2. tslib_content->editPanel:
check $this->data as in my patch

I just TYPO3 4.7 code: No fixes have been done to the code. But my understanding was, that it is more a extension programming error:

do not use:

pi_base->pi_getEditPanel('','')

pi_getEditPanel(array(''),'<table name>','',$econf));

So I would also be fine with closing this bug.