Ok

What is:
$extension = 'Demo12508';
in ...\admin\classes\model\list.php ?

protected function populateState($ordering = null, $direction = null)

$date = Demo12500HelperDates::timeFromFormat($value, $matches[1]);

$value = Demo12500HelperDates::toSql($jdate);

Warm regards
vlemos

Those are mistakes.
I'll fix that.

Moved to New ticket.

Replace with the alias of your component.

It is because when I work on the source, I copy the generated source back to the templates libraries, and I forgot to replace some strings. It contains wrong code.
This is a big mistake from me.

Will be fixed tomorrow.

Fixed.