fix: correctly encode nested struct/array params

[callmehiphop]

Fixes #437

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[codecov]

Codecov Report

Merging #439 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #439      +/-   ##
=========================================
+ Coverage    99.4%   99.4%   +<.01%     
=========================================
  Files           4       4              
  Lines         672     674       +2     
  Branches      188     189       +1     
=========================================
+ Hits          668     670       +2     
  Misses          2       2              
  Partials        2       2

Impacted Files	Coverage Δ
src/index.ts	98.48% <100%> (+0.01%)	⬆️

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