I'm trying to hook this up to an automatically generated Ruby backend, so I'm almost sure that the root cause is on my end, but I'm not sure what else to check :)

I've cloned the repo & built the example, then copied graphql.min.js, graphql.css, and index.html into my own project. I tweaked the fetcher a bit to point at my endpoint and include cookies.

At this point, when I load the page, GraphiQL makes its request for the schema, and I can see the expected result coming back:

(full dump)

However, I don't get any type hinting, and when I try to submit a query, I get an error:

I can see it's coming from here:

Which is here: https://github.com/graphql/graphql-js/blob/81a7d7add03adbb14dc852bbe45ab030c0601489/src/utilities/TypeInfo.js#L125-L127

So ... somehow that local variable schema is undefined. I know I'm a long way down a lonely road, but do you have any suggestion what I can check next? Do you think my endpoint is responding properly? Is there something else I can test?