Ensure current view and selection lookups on Tabulator handle None case

[philippjfr]

Fixes #7852

[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 87.09%. Comparing base (f331909) to head (f26e1f0).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
panel/widgets/tables.py	40.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #7858       +/-   ##
===========================================
+ Coverage   47.49%   87.09%   +39.59%     
===========================================
  Files         334      346       +12     
  Lines       50597    53018     +2421     
===========================================
+ Hits        24032    46175    +22143     
+ Misses      26565     6843    -19722     

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[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.