1. Use `textContent` instead of `innerHTML` to fix
https://github.com/go-gitea/gitea/security/code-scanning/170.
2. Clean up surrounding code to remove unnecessary `if` checks on
elements that are guaranteed to exist.
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Co-authored-by: Claude (Opus 4.6) <noreply@anthropic.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>