fix: unknown ostype when getting an index should probably create an error

[paulgmiller]

Reason for Change:
Unknown ostype when getting an index should probably create an error
Today it just returns zero. Not sure if this is a real problem but popped up in our unittests that consume this package.

Issue Fixed:

Can create an issue but my face was already in the code :)

Requirements:

• [fix ] uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

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[codecov]

Codecov Report

Merging #2681 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2681      +/-   ##
==========================================
+ Coverage   71.82%   71.82%   +<.01%     
==========================================
  Files         134      134              
  Lines       25099    25101       +2     
==========================================
+ Hits        18028    18030       +2     
  Misses       6015     6015              
  Partials     1056     1056

[jackfrancis]

/lgtm

thanks @paulgmiller

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis, paulgmiller

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