Unable to use "Subscription" as a __typename value

[andrewescutia]

When 'Subscription' is used as a __typename, the caching mechanism confuses it for the operation type and doesn't properly cache the list of items. This is done during the normalization efforts of the response so I'm uncertain if this would fall under this project or the Normalize package.

It also appears that this was an issue within the Apollo Client that was deemed appropriate and corrected: https://github.com/apollographql/apollo-client/issues/6911

example query:

query {  
     viewer {  
    user {
      subscriptions {
        __typename
        items {
          __typename
        }
      }
    }
  }
}

example response

{
  "data": {
    "viewer": {
      "user": {
        "subscriptions": {
          "__typename": "Subscriptions",
          "items": [
            {
              "__typename": "Subscription",
              "name": "Andrew"
            },
            {
              "__typename": "Subscription",
              "name": "Bob"
            }
          ]
        }
      }
    }
  }
}

the data looks something like this after re-read from cache.

{
  "user": {
    "subscriptions": {
      "items": [
        {
          "name": "Bob"
        },
        {
          "name": "Bob"
        }
      ]
    }
  }
}

[andrewescutia]

moving issue over to https://github.com/gql-dart/ferry