Change Logger Level from Error to Warn for SPA Loader

[IllianiCBT]

Adjusted the logging level from error to warn when restoring an SPA fails. This avoids an error dialog appearing whenever a character with a no-longer existing SPA is loaded. Instead, it will report to the log and advance to the next SPA.

Closes #4890

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.45%. Comparing base (caef4d9) to head (876131a).
Report is 17 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #4893      +/-   ##
============================================
- Coverage     10.46%   10.45%   -0.01%     
+ Complexity     6017     6008       -9     
============================================
  Files           952      952              
  Lines        132755   132755              
  Branches      19308    19308              
============================================
- Hits          13894    13884      -10     
- Misses       117516   117521       +5     
- Partials       1345     1350       +5     

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