fixed bug with empty constructors

[kragol]

fixes #85

[bkamins]

Thank you for reporting. Could you please add tests for the changed methods?

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.58% :tada:

Comparison is base (1bb9c95) 87.97% compared to head (fe23cfd) 88.56%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #86      +/-   ##
==========================================
+ Coverage   87.97%   88.56%   +0.58%     
==========================================
  Files           1        1              
  Lines         341      341              
==========================================
+ Hits          300      302       +2     
+ Misses         41       39       -2     

Files Changed	Coverage Δ
src/PooledArrays.jl	88.56% <100.00%> (+0.58%)	:arrow_up:

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[kragol]

Tests added.

[bkamins]

I have added some more tests. Thank you for contributing.