fix: adds null check before accessing skill property

[Scoppio]

I dont know of any bug in particular that called for this, however when checking the save from the issue #4529 I encountered this error, where it was looking for a specific skill that the person didnt had loaded, so when trying to open the person contextual menu it threw a null pointer exception.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.49%. Comparing base (519101f) to head (318ec88).
Report is 42 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5252      +/-   ##
============================================
- Coverage     10.50%   10.49%   -0.01%     
  Complexity     6044     6044              
============================================
  Files           957      957              
  Lines        134716   134726      +10     
  Branches      19572    19578       +6     
============================================
- Hits          14149    14144       -5     
- Misses       119216   119228      +12     
- Partials       1351     1354       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.