GraphQL error: "Cannot use 'in' operator to search for 'hasNext' in undefined"

[danwahl]

As of pretty recently (Oct 13?) I've been getting GraphQL errors on queries that were previously working (most of the time). Here's an example that fails in the Yoga GraphiQL IDE:

{
  questions(first: 100) {
    pageInfo {
      hasNextPage
      endCursor
    }
    edges {
      node {
        id
        fetched
        history {
          options {
            name
            probability
          }
          qualityIndicators {
            stars
            numForecasters
            numForecasts
          }
        }
      }
    }
  }
}

And the error:

{
  "errors": {
    "message": "Cannot use 'in' operator to search for 'hasNext' in undefined",
    "stack": "TypeError: Cannot use 'in' operator to search for 'hasNext' in undefined\n    at https://unpkg.com/@graphql-yoga/[email protected]/dist/yoga-graphiql.es.js:34989:101\n    at https://unpkg.com/@graphql-yoga/[email protected]/dist/yoga-graphiql.es.js:36035:13"
  }
}