Notice: Undefined index: shipping_carrier_code is returned instead of 'Required parameter "shipping_carrier_code" is missing'

[TomashKhamlai]

Preconditions (*)

1. Registered Customer
2. Virtual Product
3. Developer mode

Steps to reproduce (*)

1. Generate Customer token
2. Create empty cart as Registered Customer from GraphQL Client
3. Add virtual product to cart from GraphQL Client but use

...
    cart {
      items {
        id
...

in output
4. Get ADDRESS_ID by hovering 'Change Billing Address' or 'Change Shipping Address'

5. Execute:

mutation {
  setShippingMethodsOnCart(
    input: {
      cart_id: "{{ CART_ID }}"
      shipping_methods: {
        cart_address_id: {{ ADDRESS_ID }}
        method_code: "flatrate"
        carrier_code: "flatrate"
      }
    }
  ) {
    cart {
      available_payment_methods {
        code
        title
      }
      shipping_addresses {
        city
        available_shipping_methods {
          carrier_title
          error_message
          method_title
          method_code
          price_excl_tax
          price_incl_tax
        }
        selected_shipping_method {
          amount
        }
      }
    }
  }
}

Expected result (*)

1. According to code

        if (!$shippingMethod['shipping_carrier_code']) {
            throw new GraphQlInputException(__('Required parameter "shipping_carrier_code" is missing'));

message
Required parameter "shipping_carrier_code" is missing'
is expected

Actual result (*)

1. Notice: Undefined index: shipping_carrier_code

{
  "errors": [
    {
      "debugMessage": "Notice: Undefined index: shipping_carrier_code in /var/www/html/m2-test/app/code/Magento/QuoteGraphQl/Model/Resolver/SetShippingMethodsOnCart.php on line 75",
      "message": "Internal server error",
      "category": "internal",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "setShippingMethodsOnCart"
      ]
    }
  ],
  "data": {
    "setShippingMethodsOnCart": null
  }
}

[naydav]

#405