[FIX] point_of_sale: null value set quantity

Before this fix, when clicking on the delete button from the product screen, when the decrease quantity popup was supposed to be shown, there was a null value issue and thus a traceback.
With this fix, we force the value to be 0 instead of null.

closes odoo/odoo#92854

Signed-off-by: Masereel Pierre <pim@odoo.com>

addons/l10n_fr_pos_cert/static/src/css/pos.css

@@ -1,3 +1,3 @@
 .oldPrice {
     font-weight: bold;
-}
+}

addons/point_of_sale/static/src/js/models.js

@@ -1309,7 +1309,7 @@ class Orderline extends PosModel {
             this.order.remove_orderline(this);
             return true;
         }else{
-            var quant = typeof(quantity) === 'number' ? quantity : (field_utils.parse.float('' + quantity) || 0);
+            var quant = typeof(quantity) === 'number' ? quantity : (field_utils.parse.float('' + (quantity ? quantity : 0 )));
             if (this.refunded_orderline_id in this.pos.toRefundLines) {
                 const toRefundDetail = this.pos.toRefundLines[this.refunded_orderline_id];
                 const maxQtyToRefund = toRefundDetail.orderline.qty - toRefundDetail.orderline.refundedQty