Use wrap errors and update tests

[moisesvega]

Use wrap error verb (%w) in some fmt.Errorf calls and update some test to avoid confusion about how to get errors and compared them.

This resolves #988

[codecov]

Codecov Report

Merging #1032 (751ab8f) into master (5f5dc19) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1032      +/-   ##
==========================================
+ Coverage   98.04%   98.09%   +0.05%     
==========================================
  Files          39       39              
  Lines        1994     1995       +1     
==========================================
+ Hits         1955     1957       +2     
+ Misses         31       30       -1     
  Partials        8        8              

Impacted Files	Coverage Δ
app.go	96.21% <ø> (ø)
annotated.go	99.17% <100.00%> (+0.16%)	⬆️
provide.go	100.00% <100.00%> (ø)

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