panic `resolve() must be implemented by non-object output types` with badly formatted query

[craiga]

Describe the bug

A badly formatted query can result in a panic: resolve() must be implemented by non-object output types.

To Reproduce

Using the API at https://github.com/MHRA/products/tree/4b8712cb9f7b1b15d3f120db8792d4033586343e/medicines/api, I was trying to use the following query:

{
  products(searchTerm: "IBUPROFEN") {
    edges {
      node {
        id
      }
    }
    pageInfo
  }
}

Note that pageInfo should have stuff underneath it such as hasPreviousPage.

In GraphiQL, this shows:

{
  "message": "The network connection was lost."
}

On the server, we see:

thread 'actix-rt:worker:6' panicked at 'resolve() must be implemented by non-object output types', <::std::macros::panic macros>:2:4

Expected behavior

An error message in GraphiQL explaining that the query was badly formatted.

Additional context

I'm quite new to Rust and GraphQL, so apologies that this isn't the greatest bug report of all time. I blogged about this error and was asked to report it here.

[davidpdrsn]

Thanks for the bug report! Sounds like this should have been caught in the query validation phase. Does running this to reproduce the bug require anything besides Rust? It would be nice to have a simple way to reproduce it that didn't require lots of dependencies.