[FIX] delivery_multii_desination: set dummy product if no products from child_ids

Author: Kosaaaaa

delivery_multi_destination/__manifest__.py

@@ -13,5 +13,5 @@
     "installable": True,
     "depends": ["delivery"],
     "demo": ["demo/delivery_carrier_demo.xml"],
-    "data": ["views/delivery_carrier_view.xml"],
+    "data": ["data/product_product.xml", "views/delivery_carrier_view.xml"],
 }

delivery_multi_destination/data/product_product.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<odoo>
+
+    <record model="product.product" id="dummy_shipping_product">
+        <field name="name">DUMMY Shipping Product</field>
+        <field name="type">service</field>
+        <field name="categ_id" ref="delivery.product_category_deliveries" />
+        <field name="sale_ok" eval="False" />
+        <field name="purchase_ok" eval="False" />
+        <field name="list_price">0.0</field>
+        <field name="invoice_policy">order</field>
+    </record>
+
+</odoo>

delivery_multi_destination/models/delivery_carrier.py

@@ -30,7 +30,7 @@ class DeliveryCarrier(models.Model):
     def _onchange_destination_type(self):
         """Define the corresponding value to avoid creation error with UX."""
         if self.destination_type == "multi" and self.child_ids and not self.product_id:
-            self.product_id = fields.first(self.child_ids.product_id)
+            self.product_id = fields.first(self.child_ids.product_id) or self.env.ref('delivery_multi_destination.dummy_shipping_product')
 
     def search(self, args, offset=0, limit=None, order=None, count=False):
         """Don't show by default children carriers."""