fix(challenge): improved logging

[cnlangzi]

Changes

Fixes

• improved logging for challenge.

Tests

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• 0chain:
• gosdk:
• system_test:
• zboxcli:
• zwalletcli:
• Other: ...

[codecov-commenter]

Codecov Report

Merging #769 (d99a72e) into staging (fe23ab8) will increase coverage by 0.03%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           staging     #769      +/-   ##
===========================================
+ Coverage    24.37%   24.41%   +0.03%     
===========================================
  Files           77       77              
  Lines         7818     7826       +8     
===========================================
+ Hits          1906     1911       +5     
- Misses        5646     5648       +2     
- Partials       266      267       +1     

Flag	Coverage Δ
Unit-Tests	24.41% <ø> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...et/blobbercore/handler/object_operation_handler.go	33.05% <0.00%> (+0.33%)	⬆️

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[ssardana08]

lgtm

[peterlimg]

lgtm