Adding a check in onHookEnd to only call error function if it exists and is a function (fixes #482)

[jamesmortensen]

Context

Checklist

• Sign Allure CLA
• Provide unit tests

Fixes #482

The issue here is that, when running mocha in parallel mode with beforeEach or afterEach hooks, the onEndHook is called in MochaAllureReporter and the error() method is undefined.

Not sure about any unit tests for this. The project unit tests weren't passing before I made changes, so it's difficult to work with broken tests. Instead, I have a reproduceable example here: https://github.com/jamesmortensen/allure-js-reporter-issues#when-run-in-parallel-mode-with-hooks-hookerror-is-not-a-function

In the reproduceable example, run npx mocha -p test-with-hooks.js without the changes, to see the error occur, and run it with the changes to see the reporter function without errors and somewhat correctly. (By somewhat correctly, there is this related issue #485 where failed test cases in parallel mode are incorrectly reported as yellow/broken instead of red/failed.)

[epszaw]

Could we set default value for hook.error? Like just stub function to avoid additional conditions?
Or we can use optional chaining operator to reach the same result:

this.coreReporter.endHook(hook?.error?.());

[jamesmortensen]

@epszaw I will give it a try later in the month when I get some more time. Thanks for the feedback.

[jamesmortensen]

Hi @epszaw I just got back around to looking at this. It looks like we can close this pull request. I can see you added this change in this commit: cbb3426. Thanks for adding it in.