UI: Wrap unreachable code in comment to fix clang warnings

The branch is never taken and the code acts as documentation for a
(possible) future use case. According to YAGNI it could be removed
entirely, wrapping it in a comment is the less destructive approach.
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Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f