fix: Workaround an edge case exception in AmendmentCenter

[godexsoft]

Fixes #2881

From my tests the output of account_info is now identical with xrpld.
I'd like to investigate this further in the future and possibly find a better fix if there is one in #2895

[codecov]

Codecov Report

❌ Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.86%. Comparing base (e733fad) to head (ce0e875).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/data/AmendmentCenter.cpp	63.63%	1 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2897      +/-   ##
===========================================
- Coverage    81.86%   81.86%   -0.01%     
===========================================
  Files          382      382              
  Lines        14506    14510       +4     
  Branches      7960     7963       +3     
===========================================
+ Hits         11876    11878       +2     
  Misses        1451     1451              
- Partials      1179     1181       +2     

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