fix: Clean up vanilla proof fetching errors for proper display

[RobQuistNL]

Results;

2  0  2374  good
2  0  2409  good
2  0  2282  bad (generating vanilla proof: non-200 code from http://10.224.3.83:1123/remote/vanilla/single: 'fsstat: path not found
')
2  0  2579  good
2  0  2338  good

This PR should change that to;

2  0  2374  good
2  0  2409  good
2  0  2282  bad (generating vanilla proof: non-200 code from http://10.224.3.83:1123/remote/vanilla/single: 'fsstat: path not found')
2  0  2579  good
2  0  2338  good

Related Issues

Proposed Changes

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Checklist

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• The PR title is in the form of of <PR type>: <area>: <change being made>
  • example: fix: mempool: Introduce a cache for valid signatures
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