Parse keystore address without 0x prefix, fix parse error logging

[eliteprox]

What does this pull request do? Explain your changes. (required)
This resolves a bug from #2713 when parsing keystore addresses without the 0x prefix. Errors from parseEthKeystorePath were also not being logged, because err was only available within the scope of if err == nil.

Specific updates (required)

• Updated logic flow in starter.go.
• Changed ethcommon.HexToAddress to ethcommon.BytesToAddress(ethcommon.FromHex(address)) in parseEthKeystorePath().
  • ethcommon.FromHex considers the 0x prefix optional.

How did you test each of these updates (required)

• Validated error logging by performing a functional test with valid/invalid JSON, file not found, and bad JSON format
• Validated address parsing with/without 0x prefix.
• Updated unit test TestParse_ParseEthKeystorePathValidFile

Does this pull request close any open issues?
Fixes #2757

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

Merging #2759 (5f0344d) into master (a8f3f4e) will decrease coverage by 0.00294%.
The diff coverage is 25.00000%.

@@                 Coverage Diff                 @@
##              master       #2759         +/-   ##
===================================================
- Coverage   56.30182%   56.29888%   -0.00294%     
===================================================
  Files             88          88                 
  Lines          19177       19178          +1     
===================================================
  Hits           10797       10797                 
- Misses          7788        7789          +1     
  Partials         592         592                 

Impacted Files	Coverage Δ
cmd/livepeer/starter/starter.go	4.28954% <25.00000%> (-0.00384%)	⬇️

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Impacted Files	Coverage Δ
cmd/livepeer/starter/starter.go	4.28954% <25.00000%> (-0.00384%)	⬇️

[leszko]

Thanks for the fix @eliteprox