Why below SQL query is showing a syntax error in MySQL?

SELECT IFNULL(customer.cust_name, 'N/A') as customer_name

, IFNULL(product.prod_name, 'N/A') as product_name

, IFNULL(invoice_item.quantity, 0) as quantity

FROM ((customer

LEFT OUTER JOIN invoice ON customer.id = invoice.cust_id)

LEFT OUTER JOIN invoice_item ON invoice_item.invoice_id = invoice.id)

LEFT OUTER JOIN product ON invoice_item.product_id = product.id

ORDER BY customer.id, product.id;