in the following code amount is assigned to price_unit,
invoice_line_id = self.env['account.move.line'].create({                                'name':std_fee_id.fee_item_id.name,                                'move_id': invoice_rec.id,                                'product_id': product_id.related_product.id,                                #'fiscalyear_month_id': std_fee_id.fiscalyear_month_id.id,                                'price_unit': float(std_fee_id.amount),                                'account_id': product_id.property_account_income_id.id,                                })
 
                        
hi Niyas Raphy,
after adding that code now it gives me this user error:
User Error
Cannot create unbalanced journal entry. Ids: [59] Differences debit - credit: [-1500.0]
pass this in context: with_context(check_move_validity=False)