fix(cel): add nil checks to prevent panics in webhook parsers

[theakshaypant]

📝 Description of the Change

Add comprehensive nil pointer checks in PopulateEvent methods for webhook parsers to prevent panics when accessing nested fields that may be nil or missing from webhook payloads.

👨🏻‍ Linked Jira

https://issues.redhat.com/browse/SRVKP-9396

🔗 Linked GitHub Issue

N/A

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[gemini-code-assist]

Summary of Changes

Hello @theakshaypant, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical stability issue by introducing robust nil pointer checks in the webhook parsing logic for GitHub, GitLab, and Gitea events. The primary goal is to prevent application panics that could occur when webhook payloads lack expected nested fields, thereby enhancing the overall resilience and reliability of event processing.

Highlights

• Enhanced Robustness: Implemented comprehensive nil pointer checks within the PopulateEvent methods across GitHub, GitLab, and Gitea webhook parsers.
• Panic Prevention: These checks specifically target nested fields in webhook payloads, preventing potential panics when data is missing or nil.
• Improved Event Handling: Ensures that event processing continues gracefully even with incomplete webhook data, leading to more stable system behavior.

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[gemini-code-assist]

Code Review

This pull request is a great improvement for robustness, adding necessary nil checks to the webhook parsers to prevent panics. The changes are well-implemented across GitHub, GitLab, and Gitea parsers. The addition of unit tests to cover these new checks is also excellent. I've made a couple of suggestions to refactor the IssueCommentEvent handling in both the GitHub and Gitea parsers to improve readability and avoid redundant checks. Overall, this is a solid fix.

[aThorp96]

/approve

I think the Github handling specifically might be unnecessary, but overall lgtm. Thanks for the fix!

[zakisk]

@theakshaypant can you please address Andrew's comments so that we can merge this?

[theakshaypant]

Thanks @aThorp96 for pointing out GetFoo being nil safe. Have reverted all but one check in the github parsing in the interest of keeping the cyclomatic complexity low where possible.

[aThorp96]

/lgtm