Add a sanity check before writing out results

[Andrew-S-Rosen]

Summary of Changes

Add a sanity check to I/O.

Checklist

• I have read the "Guidelines" section of the contributing guide. Don't lie! 😉
• My PR is on a custom branch and is not named main.
• I have added relevant, comprehensive unit tests.

Notes

• Your PR will likely not be merged without proper and thorough tests.
• If you are an external contributor, you will see a comment from @buildbot-princeton. This is solely for the maintainers.
• When your code is ready for review, ping one of the active maintainers.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.11%. Comparing base (801d58e) to head (b40b196).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2027   +/-   ##
=======================================
  Coverage   99.11%   99.11%           
=======================================
  Files          81       81           
  Lines        3272     3274    +2     
=======================================
+ Hits         3243     3245    +2     
  Misses         29       29           

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