Fallback introspection query never actually happens

[dallonf]

Just starting messing with GraphiQL and the graphql-java implementation, which doesn't support subscriptionType yet. According to #55, this was fixed with a fallback query, but it seems to be implemented by catching the fetcher's result.

The thing is... it appears that the fetcher is not actually supposed to (and, at least in the example directory, does not) throw, at least in the case of a standard GraphQL error!

For reference, the result that is returned when introspection fails is this:

{
  "errors": [
    {
      "validationErrorType": "FieldUndefined",
      "message": "Validation error of type FieldUndefined: Field subscriptionType is undefined",
      "locations": [
        {
          "line": 6,
          "column": 7
        }
      ],
      "errorType": "ValidationError"
    }
  ],
  "data": null
}

I also tried manually throwing in the fetcher if the result contains errors; this works, but degrades the user experience as normal validation errors will not show up in the right-hand panel.

[sazzer]

I've just come across this myself, and I can't actually find subscriptionType mentioned in the GraphQL Specification anywhere. It looks like this turned up in the graphql-js codebase back in September, as commit 8a589f6, and GraphiQL has just inherited it automatically as a dependency.

[leebyron]

Thanks for reporting this and sorry for the delay in fixing. Subscriptions is an experimental feature, and GraphiQL has growing experimental support.