[php] trying to get property of non-object

Selamat siang master-master yang ada di sini, mohon bantuannya dong saya sedang membuat program untuk menampilkan transaksi, dan permasalahannya adalah ketika saya mau menampilkan 'value' dari level pegawai:

Eror yang tampil adalah: A PHP Error was encountered Severity: Notice

Message: Trying to get property of non-object

Filename: penjualan/v_Penjualan.php

Line Number: 52

Backtrace:

File: C:\xampp\htdocs\tokobuku\application\views\admin\penjualan\v_Penjualan.php Line: 52 Function: _error_handler

File: C:\xampp\htdocs\tokobuku\application\controllers\admin\Penjualan.php Line: 28 Function: view

File: C:\xampp\htdocs\tokobuku\index.php Line: 315 Function: require_once

Coding controller saya:

if($this->session->userdata('employee_id') != Null)
		{
			$id = $this->session->userdata('level_id');
			$data = array(
				'user_level' => $this->level_model->level_getById($id)->row(),
				'book' => $this->penjualan_model->book_getAll(),
				'book1' => $this->penjualan_model->book_getAll1(),
				'book2' => $this->penjualan_model->book_getAll2(),
				'customer' =>$this->customer_model->customer_getAll(),


			);

Coding dari view saya:

    <div class="col-sm-8">
                                                    <input type="text" class="form-control" data-employee="employee" value="<?= $user_level->name; ?>" readonly>
                                                </div>

Terimakasih