Improve tests coverage

[dstranz]

No description provided.

[codecov]

Codecov Report

Merging #10 into master will increase coverage by 3.96%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #10      +/-   ##
==========================================
+ Coverage      82%   85.96%   +3.96%     
==========================================
  Files          20       21       +1     
  Lines         989     1012      +23     
==========================================
+ Hits          811      870      +59     
+ Misses        178      142      -36

Impacted Files	Coverage Δ
Tests/ErrorsTests.swift	100% <100%> (ø)
Sources/Networking/Errors.swift	97.29% <0%> (+97.29%)	⬆️

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