Add missing if statement in #waitForCondition

[camertron]

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What are you trying to accomplish?

When refactoring our usage of MutationObservers in SelectPanelElement, I completely forgot a necessary if statement that guards against the possibility that the condition has still not been met when the contents of the component's DOM tree change.

Integration

No changes necessary in production.

Risk Assessment

• Low risk the change is small, highly observable, and easily rolled back.
• Medium risk changes that are isolated, reduced in scope or could impact few users. The change will not impact library availability.
• High risk changes are those that could impact customers and SLOs, low or no test coverage, low observability, or slow to rollback.

Accessibility

• No new axe scan violation - This change does not introduce any new axe scan violations.

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🦋 Changeset detected

Latest commit: 586c54f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@primer/view-components	Patch

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