**Steps to reproduce:**
* Install  `point_of_sale` module.
* Go to Settings:
     * Enable Lots & Serial Numbers.
     * Enable Variants.
     * Set Barcode Nomenclature to Default GS1 Nomenclature.
* Create a product:
     * Enable Track Inventory set to By Lots.
     * Under Attributes & Variants:
     * Add an attribute with two values and save.
* Generate product variants:
     * Open one variant and set barcode to 5123648695416.
* Update inventory:
     * Go to the main product (template).
     * Update On Hand Quantity:
             * Update On Hand Quantity with a lot/serial number:
               010512364869541610784512.
             * Select the variant with the defined barcode.
* Under Point of Sale tab:
    * Set a POS Category.
* Open a POS session and scan:
010512364869541610784512.

**Observed behavior:**
* Scanning the GS1 barcode in POS raises a traceback:
  *TypeError: Cannot read properties of undefined (reading
  'product_template_attribute_value_ids')*.

**Cause:**

[Scans GS1 barcode: 010512364869541610784512]
│
├─ ProductScreen._barcodeGS1Action(parsed_results)
│    • product = await _getProductByBarcode(productBarcode)  ✅ found
│    • calls `addLineToCurrentOrder(vals, { code: lotBarcode })`
│                                                              ⚠️ only `lotBarcode` passed, `productBarcode` discarded
│
├─ PosStore.addLineToCurrentOrder() → addLineToOrder()
│    • product has variants → isConfigurable() = true
│
├─ PosStore.handleConfigurableProduct()
│    • calls openConfigurator(productTemplate, { ...opts })
│      opts = { code: lotBarcode }
│
└─ PosStore.openConfigurator()
     • opts.code = lotBarcode  → truthy → enters if(opts.code) branch
     • getBy("barcode", opts.code.base_code)
     •  getBy("barcode", "784512")   ← "784512" is a LOT number, not a product barcode!
       → returns undefined ❌
     • product packaging lookup also fails → undefined ❌
     • product = undefined
     │
     └─ attributeLinesValues.map(values =>
            values.filter(value =>
                product.product_template_attribute_value_ids.includes(value)
                ^^^^^^^ undefined  → 💥 TypeError

**Fix:**
* Pass the product from `handleConfigurableProduct` to the configurator.
* If no product is found using `opts.code`, use the passed product
  instead.

---

opw-6031909

Forward-Port-Of: odoo/odoo#257227
Forward-Port-Of: odoo/odoo#254572