fix: check for nil ValidTo so it'll go to the dead letter queue

[evq]

Summary

adds a missing check to ensure ValidTo is not nil ( not just ValidTo.Value(). )

I think the case that led to this happening was a quirk of long past testing on the development environment, but might as well add the check.

Type of Change

• Product feature
• Bug fix
• Performance improvement
• Refactor
• Other

Tested Environments

• Development
• Staging
• Production

Before Requesting Review

• Does your code build cleanly without any errors or warnings?
• Have you used auto closing keywords?
• Have you added tests for new functionality?
• Have validated query efficiency for new database queries?
• Have documented new functionality in README or in comments?
• Have you squashed all intermediate commits?
• Is there a clear title that explains what the PR does?
• Have you used intuitive function, variable and other naming?
• Have you requested security and/or privacy review if needed
• Have you performed a self review of this PR?

Manual Test Plan

[clD11]

LGTM Approved