Correct error handling from remote backend

[MichalFikejs]

This pull request is solving the issue that we encountered on our project.

Basically, the problem is that errors are not in the correct format, that means that you will get no sense error, which cannot help you.

Expected:
When my remote schema fails, I would love to get the error through my local schema.

Reality:
I will get just [object Object] as a message.

This pull request solves it.

In both cases in examples below, remote backend responded with the same result.

Result before:

{
  "errors": [
    {
      "message": "[object Object]",
      "locations": [
        {
          "line": 31,
          "column": 3
        }
      ],
      "path": [
        "pub_verifyMe"
      ]
    }
  ],
  "data": null
}

Result after:

{
  "errors": [
    {
      "message": "Invalid address.",
      "path": [
        "pub_verifyMe"
      ],
      "extensions": {
        "code": "BAD_USER_INPUT",
        "exception": {
          "invalidArgs": [
            "blockchainAddress"
          ],
          "stacktrace": [
            "UserInputError: Invalid address.",
            "    at /app/dist/graphql/verify/resolvers.js:76:40",
            "    at step (/app/dist/graphql/verify/resolvers.js:32:23)",
            "    at Object.throw (/app/dist/graphql/verify/resolvers.js:13:53)",
            "    at rejected (/app/dist/graphql/verify/resolvers.js:5:65)",
            "    at <anonymous>"
          ]
        }
      }
    }
  ],
  "data": null
}

[apollo-cla]

@MichalFikejs: 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/

[avilaj]

any progress with this pr?

[MichalFikejs]

@benjamn @hwillson Any comments on this?

[yaacovCR]

Not directed at me but I basically took same approach in the fork. See #1206

[yaacovCR]

Closed in favor of #1307