test: Add assertions to testNSException

[philipphofmann]

Assert type and value for testNSException.

Follow up on #6653.

#skip-changelog

Closes #6657

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.163%. Comparing base (a4e1541) to head (155d7ce).
⚠️ Report is 7 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #6656       +/-   ##
=============================================
+ Coverage   84.960%   85.163%   +0.202%     
=============================================
  Files          452       452               
  Lines        27668     27668               
  Branches     12115     12117        +2     
=============================================
+ Hits         23507     23563       +56     
+ Misses        4113      4057       -56     
  Partials        48        48               

see 9 files with indirect coverage changes

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[philprime]

LGTM