Lots of ID null logs

@afrisalyp - We finally got the latest code deployed in prod. I'm seeing this a lot for Github tickets in the logs:

error: Error happened in process
TypeError: Cannot read property 'id' of null
    at handleIssueLabelUpdated (/topcoder-x-processor/services/IssueService.js:578:47)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)
error:  message=Cannot read property 'id' of null, stack=TypeError: Cannot read property 'id' of null
    at handleIssueLabelUpdated (/topcoder-x-processor/services/IssueService.js:578:47)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7), logged=true

It doesn't seem to affect functionality, but it's something we should clean up, thanks.

Final Submission Guidelines

Git issue link: https://github.com/topcoder-platform/topcoder-x-ui/issues/232