Consistently use lower case for errors with no ending punctuation

[masih]

Fixes #795

[codecov]

Codecov Report

Attention: Patch coverage is 6.25000% with 15 lines in your changes missing coverage. Please review.

Project coverage is 69.39%. Comparing base (1b17c6c) to head (8d9e568).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
manifest/manifest.go	0.00%	12 Missing ⚠️
f3.go	50.00%	1 Missing ⚠️
gpbft/gpbft.go	0.00%	1 Missing ⚠️
internal/powerstore/powerstore.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #796      +/-   ##
==========================================
- Coverage   69.64%   69.39%   -0.26%     
==========================================
  Files          77       77              
  Lines        7900     7900              
==========================================
- Hits         5502     5482      -20     
- Misses       1949     1965      +16     
- Partials      449      453       +4     

Files with missing lines	Coverage Δ
certstore/certstore.go	64.41% <ø> (ø)
f3.go	61.53% <50.00%> (-1.47%)	⬇️
gpbft/gpbft.go	89.12% <0.00%> (ø)
internal/powerstore/powerstore.go	61.86% <0.00%> (ø)
manifest/manifest.go	54.19% <0.00%> (ø)

... and 3 files with indirect coverage changes