fix: use `hasOwnProperty` for key existence check

[kricsleo]

resolves #282

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.60%. Comparing base (d283cf5) to head (0457caf). Report is 80 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #286      +/-   ##
==========================================
+ Coverage   95.27%   97.60%   +2.33%     
==========================================
  Files           7        7              
  Lines         867      711     -156     
  Branches      187      240      +53     
==========================================
- Hits          826      694     -132     
+ Misses         41       17      -24     

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[pi0]

We need to use an object with null proto.

[kricsleo]

We need to use an object with null proto.

@pi0 This object will be returned for the user to use, and they may expect it to behave like a normal object with prototype functions (e.g., calling .toString() for their own purposes). A "null proto" would break their code.

If this object is only for internal use, that's fine since we control how it's used. But if it's exposed to users, are you still okay with that? 🤔

[pi0]

It wouldn't break user expectations, and using null proto objects is pretty standard way to help this issue.

[pi0]

Thanks 🙏🏼