Fix JS error when share button is missing on project list (#6154)

[Aaditya0411]

Description

This PR adds a null-check before attaching the click handler to the project share button.

In some cases, the share button element is not present in the DOM, which caused a JavaScript error when navigator.share was available.

Changes

• Added a safe null-check before calling addEventListener on the share button
• Prevents runtime JS errors on the project list page

Related Issue

Fixes #6154

[Aaditya0411]

Hi maintainers 👋
This is my first contribution to Catroweb.
Please let me know if any changes or improvements are required.
Thanks for reviewing!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.94%. Comparing base (8a585eb) to head (9cfe3db).
⚠️ Report is 30 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #6155      +/-   ##
=============================================
- Coverage      51.94%   51.94%   -0.01%     
  Complexity      7964     7964              
=============================================
  Files            733      733              
  Lines          25569    25569              
=============================================
- Hits           13282    13281       -1     
- Misses         12287    12288       +1     

Flag	Coverage Δ
behat	49.70% <ø> (-0.01%)	⬇️
phpunit	10.38% <ø> (ø)

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