It seems a bug, please help to change to:

    public function toTableArray()
    {
        if ($this->count()>0) {
            $result = array(
                array_keys($this->data[0])
            );
            
            foreach ($this->data as $rows) {
                array_push($result, array_values($row));
            }
            return $result;
        }
        return [
            array_keys($this->meta["columns"])
        ];
    }