Issues on ES5 with babel polyfill (AsyncGenerator has no Symbol.asyncIterator)

[tsteinholz]

On ES5 environments, merging Schemas and Resolvers via the addResolversToSchema function is able to execute, but it always results in Error: Unexpected schema type: YourGraphQLTypeHere.

Or when I am running locally with the https://github.com/svaarala/duktape js engine.

TypeError: cannot read property [Symbol wellknown '?Symbol.iterator?'] of undefined
    at [anon] (duk_hobject_props.c:2549) internal
    at _createForOfIteratorHelper (code/services/testingGraphQLTools/testingGraphQLTools.js:9656) strict
    at visitTypeSources (code/services/testingGraphQLTools/testingGraphQLTools.js:10820) strict
    at mergeGraphQLTypes (code/services/testingGraphQLTools/testingGraphQLTools.js:10856) strict
    at mergeTypeDefs (code/services/testingGraphQLTools/testingGraphQLTools.js:10805) strict
    at testingGraphQLTools (code/services/testingGraphQLTools/testingGraphQLTools.js:25192)
    at [anon] (code/services/testingGraphQLTools/testingGraphQLTools.js:25165)
    at __webpack_require__ (code/services/testingGraphQLTools/testingGraphQLTools.js:42570)
    at [anon] (code/services/testingGraphQLTools/testingGraphQLTools.js:42636)
    at global (code/services/testingGraphQLTools/testingGraphQLTools.js:42638) preventsyield
error in executing file code/services/testingGraphQLTools/testingGraphQLTools.js

This is not due to a bug in the GraphQL tools, but a lack of functionality in the babel polyfill that is required to run in ES5 environments.

Reference to the underlying issue in babel:
babel/babel#7467

I did not mark this as a 'bug' as these tools do not advertise ES5-friendliness, however, if there were any known work-arounds then that would be greatly appreciated! Switching to an ES6 environment is not currently possible for my project.

[ardatan]

You can polyfill it by yourself, maybe?
See https://www.npmjs.com/package/iterator-polyfill