Symlinks are followed when you click on a link next to an entry, either
until a file has been found or until we know that the link is dead.
When the link cannot be accessed, we fall back to the current behavior
of showing the document containing the target.
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
1. Make the material icon falls back to basic theme correctly
2. Remove `TestAttributeReader`, the problem has been resolved.
3. Fix `toggleElem` bug and add tests
