fix: do not modify constructor options argument

[AVaksman]

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

Fixes #971

[codecov]

Codecov Report

Merging #974 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #974      +/-   ##
=========================================
+ Coverage      99%     99%   +<.01%     
=========================================
  Files          11      11              
  Lines       10657   10659       +2     
  Branches      473     473              
=========================================
+ Hits        10551   10553       +2     
  Misses        106     106

Impacted Files	Coverage Δ
src/storage.ts	100% <100%> (ø)	⬆️

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