[#56]: CheckSuite after field can be null

[AlistairB]

Issue reference: Pretty trivial, do I need one?

I just noticed there are cases where the check suite after field is null.

Submission Checklist:

• Have you followed the guidelines in our Contributing document (for example, is your tree a clean merge)?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Does your submission build?
• Does your submission pass tests?
• Have you run lints on your code locally prior to submission?
• Have you updated all of the cabal/nix infrastructure?
• Is this a breaking change? Have you discussed this?

[kvanbere]

A great contribution, tested and passed, thanks for catching this @AlistairB !

Staged for 0.16.0 .

[kvanbere]

This has been released. Thanks @AlistairB