fix purge command bug (#4619)

[bugtype]

fix purge command bug.

[codecov]

Codecov Report

Merging #4621 into master will decrease coverage by 0.06%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #4621      +/-   ##
==========================================
- Coverage   92.66%   92.59%   -0.07%     
==========================================
  Files         119      119              
  Lines        8560     8562       +2     
==========================================
- Hits         7932     7928       -4     
- Misses        628      634       +6

Impacted Files	Coverage Δ
src/Routers/PurgeRouter.js	83.33% <50%> (-6.67%)	⬇️
src/RestWrite.js	93.05% <0%> (-0.74%)	⬇️
...dapters/Storage/Postgres/PostgresStorageAdapter.js	97.11% <0%> (-0.1%)	⬇️

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[flovilmart]

Thanks for the PR @AreYouHappy !