SchemaLink incorrectly expects an execution return value to be a `Promise`

[brabeji]

Hello! I think I've found a bug:

Intended outcome:
Being able to obtain synchronous result from SchemaLink

Actual outcome:
SchemaLink incorrectly expects graphql's execute to always returns a Promise. In case of synchronous execution an Error is thrown.

How to reproduce the issue:
https://codesandbox.io/s/jjmk3jwyl3

I think this may be consequence of incorrect graphql API Reference: graphql/graphql.github.io#439

Cheers and big thank you for this awesome library!

[Neitsch]

I'm not familiar enough with this project to fix it myself, but it looks like it just needs to be wrapped in a Promise.resolve graphql/graphql-js#1115

[stubailo]

Yeah this is a breaking change in graphql@0.12, it used to always return a promise.

Mind sending a PR to always wrap it in a resolve?

[brabeji]

PR is here #354

[brabeji]

This was fixed by #354. Closing.