Fix #8737: Added Safeguard for Missing Game Options When Saving Older Campaigns

[IllianiBird]

Fix #8737

Under rare circumstances it seems that a campaign can end up with malformed MegaMek Game Options. null to be precise. This then prevents saving, because the saving process assumes GameOptions has been substantiated.

I've explored the campaign creation process and I cannot find any explanation why campaigns are instantiating with null GameOptions. It shouldn't be possible.

Clearly that isn't the case, so what I've gone ahead and done is added a catch that will self-correct in the event a null GameOption is detected during the save process. The player will be notified when this occurs.

[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 15.23%. Comparing base (9572a8c) to head (0e00370).
⚠️ Report is 19 commits behind head on main.

Files with missing lines	Patch %	Lines
MekHQ/src/mekhq/campaign/Campaign.java	20.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #9091      +/-   ##
============================================
+ Coverage     15.19%   15.23%   +0.03%     
- Complexity     9273     9310      +37     
============================================
  Files          1302     1304       +2     
  Lines        172400   172523     +123     
  Branches      26046    26063      +17     
============================================
+ Hits          26204    26281      +77     
- Misses       143151   143198      +47     
+ Partials       3045     3044       -1     

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[Sleet01]

From what I recall, we might have seen this when a campaign contained game options that were no longer supported, or when the campaign's options did not contain a value that was now required (due to a recent change in the nightly builds, say).
We'd throw an exception that wouldn't be handled until higher up the call stack than where we set the options instance, and would end up with the default null value.
But I never found the smoking gun.

[Sleet01]

LGTM