Call to a member function result() on bool

I was upgrade my php from php7.2 to php7.4. And I got error message : 

Mesage Error : ==>>>      Call to a member function result() on bool     <<<===
...

This the line that appointed by error message : 
..
      ===>>>>      return $this->db->get("pelanggan_not_pending p")->result();
..
..
The complete syntax are :
..

..
private function listPelanggan()

    {
       
        $this->db->select([
            'p.nama',
            'p.nomor_registrasi',
            'p.id',
        ]);
        $this->db->where_in("p.status", ["AKTIF"]);
        $this->db->order_by("p.nama asc");
        return $this->db->get("pelanggan_not_pending p")->result();
    }


..
So, how do I correct this error ?