Await on graphql.execute() before calling executionDidEnd handler (AS-59)

[cheapsteak]

extensionStack's executionDidEnd handler (the callback function returned from executionDidStart) was being called before graphql.execute finishes running

This PR adds an await before the return so code in finally runs after graphql.execute finishes

TODO:

• Update CHANGELOG.md with your change (include reference to issue & this PR)
• 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

[benjamn]

Makes sense!

It's usually not necessary to await a promise before returning it from an async function, because it will just get rolled into the final promise, but in this case the timing of the finally block is what matters.

[abernix]

Great find and LGTM.

As we discussed on our call: Were this execute used anywhere else besides the place where it's used, it might have been tempting to suggest wrapping the execution in a return-'d Promise.resolve with a .then(onFulfilled, onRejected) where fulfillment or rejection both called executionDidEnd() to preserve the async dynamics, but given the limited scope, this is great.

Also as discussed, a test which ensures that the duration amounts in the traces mathematically match up would be welcomed either in this PR or as a follow-up (since we could use more of those in general). Your call!

[cheapsteak]

Thanks for the reviews!
And appreciate the leeway on whether to do tests as part of this PR or separately. I think I'd prefer to split the addition of the tests into a separate PR (working on that now), as there might be quite a few some things in the tests that could warrant further discussion, whereas the fix itself is fairly straightforward

[JasonMurphy13]

Glad you guys found and fixed this so quickly! I was scratching my head for hours on this before I contacted about the issue. Eagerly awaiting the new version for my own testing!!

[abernix]

@dragonfriend0013 This has been released in 2.4.2!