refactor(location): adjust zipCode nullish checks

[ST-DDT]

This PR changes the implementation of zipCode to replace the falsy checks with explicit nullish checks.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.96%. Comparing base (79d8f2b) to head (1a60137).
Report is 1 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #3080      +/-   ##
==========================================
- Coverage   99.97%   99.96%   -0.01%     
==========================================
  Files        2776     2776              
  Lines      226260   226262       +2     
  Branches      591      592       +1     
==========================================
- Hits       226206   226193      -13     
- Misses         54       69      +15     

Files with missing lines	Coverage Δ
src/modules/location/index.ts	99.05% <100.00%> (-0.95%)	⬇️

... and 1 file with indirect coverage changes

[xDivisionByZerox]

I do not complain about this change, but has this been a problem before? Is there a GH issue I didn't notice?

[ST-DDT]

I do not complain about this change, but has this been a problem before? Is there a GH issue I didn't notice?

No, its only for consistency with our other code.