Fix: TypeError ufunc 'isnan' not supported for the input types

[gogetron]

Summary

Addresses #1063

🎯 Purpose: Fix TypeError when inputs cannot be cast using numpy safe rule.

[ ✏️ Write your summary here. ]
To avoid the exception I changed np.isnan to pd.isna as suggested in #1063. In addition, I added a new test that asserts this behavior works correctly and improved the type hints of the modified function (mypy --strict now reports 2 fewer errors). When this test is run on the current master branch it raises a TypeError exception.

Testing

🔍 Testing Done: Existing test suite and the new added test.

Links to Relevant Issues or Conversations

🔗 What Git or Slack items (Issues, threads, etc) that are specifically related to
this work? Please link them here.

#1063

References

Reviewer Notes

💡 Include any specific points for the reviewer to consider during their review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.19%. Comparing base (0221f8b) to head (d1d89e2).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1096      +/-   ##
==========================================
+ Coverage   96.18%   96.19%   +0.01%     
==========================================
  Files          76       76              
  Lines        5996     6014      +18     
  Branches      992     1000       +8     
==========================================
+ Hits         5767     5785      +18     
  Misses        135      135              
  Partials       94       94              

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