fix: code copy not shown on collapsed divs

[yufeih]

Fixes #9517

https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/innerText

Note: innerText is easily confused with Node.textContent, but there are important differences between the two. Basically, innerText is aware of the rendered appearance of text, while textContent is not.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (84b7afb) 71.37% compared to head (5b22bb7) 71.37%.
Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9531   +/-   ##
=======================================
  Coverage   71.37%   71.37%           
=======================================
  Files         558      558           
  Lines       24024    24024           
  Branches     4173     4173           
=======================================
  Hits        17147    17147           
  Misses       5780     5780           
  Partials     1097     1097           

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