Maintain original errors through stitching

[alexFaunt]

We ran into the problem raised in Issue #480 whereby original errors are swallowed up when using merged schemas.

I propose simply attaching the original errors to the error object so they can be accessed downstream.

I've jumped the gun here as we really need the original error on our project, so will watch discussion on #480 and look to update when necessary

TODO:

• If this PR is a new feature, reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass
• Update CHANGELOG.md with your change

[apollo-cla]

@alexFaunt: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[freiksenet]

@alexFaunt Could you add the test for that? Otherwise it looks good.

[stubailo]

@freiksenet heads up, let's also avoid adding the version number to the changelog in the PR, since we usually do that while releasing.

[alexFaunt]

I came back to it today and tried again to add a test and I can't figure it out

in the testMergeSchemas > errors > root level, I don't see the combined error, despite the combined error being hit in the code.

I might try again when I get some time but if someone knows what i'm missing that'd be helpful 👍

[timrs2998]

It's been ~20 days with no activity. Can either the author or a maintainer update this PR?

[alexFaunt]

I honestly tried to add a test for it an failed for the above reason - if no one has the capacity to help, then this can be closed for someone with more familiarity with the codebase to redo later.

[stringbeans]

hey @alexFaunt !

i've forked the most recent version of graphql-tools and am making your proposed changes and attempting to add tests for coverage here. just letting you know :)

let me know if you have any suggestions or tips... ill attach the new PR here once its ready

[alexFaunt]

Work has been picked up by @stringbeans, thanks!