Cannot find module 'iterall' on version ˆ2.19.1

[mwebler]

After updating to version 2.19.1 of graphql-tools I started getting the following error:

Detailed stack trace: Error: Cannot find module 'iterall'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    **at Object.<anonymous> (/user_code/node_modules/graphql-tools/dist/stitching/observableToAsyncIterable.js:46:17)**
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)

For some reason, this doesn't happens when running my server locally, just when I try to deploy it to Google Cloud Functions (I have no idea why). But adding the module as a dependency to my project package.json fixed the error...

I did some investigation and, long story short, this is probably happening because PR #609 started using iterall without listing it as a dependency on package.json
So, this issue is only about adding iterall to dependencies on package.json 😄