fix: treat null responses as JSON scalars

[laststylebender14]

Summary:
Briefly describe the changes made in this PR.

Issue Reference(s):
Fixes #... (Replace "..." with the issue number)

Build & Testing:

• I ran cargo test successfully.
• I have run ./lint.sh --mode=fix to fix all linting issues raised by ./lint.sh --mode=check.

Checklist:

• I have added relevant unit & integration tests.
• I have updated the documentation accordingly.
• I have performed a self-review of my code.
• PR follows the naming convention of <type>(<optional scope>): <title>

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.13%. Comparing base (d473af2) to head (be83681).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2784   +/-   ##
=======================================
  Coverage   87.13%   87.13%           
=======================================
  Files         254      254           
  Lines       25144    25144           
=======================================
+ Hits        21909    21910    +1     
+ Misses       3235     3234    -1     

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