Log json exception details on chain config file load error

[halfalicious]

Also return new error code AlethErrors::ConfigFileInvalid

[codecov-io]

Codecov Report

Merging #5526 into master will increase coverage by 0.02%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master    #5526      +/-   ##
==========================================
+ Coverage   61.86%   61.88%   +0.02%     
==========================================
  Files         344      344              
  Lines       28755    28763       +8     
  Branches     3267     3267              
==========================================
+ Hits        17789    17800      +11     
  Misses       9797     9797              
+ Partials     1169     1166       -3

[gumb0]

I would prefer to keep json_spirit dependency inside ChainParams.cpp, i.e. handle js::Error_position in ChainParams::loadConfig and re-throw as dev::Exception-derived exception.

(There is already some validation of json in loadConfig, that does this (see validateConfigJson). Also it logs directly to std::error, I think you may do the same)

[halfalicious]

at does this (see validateConfigJson). Also it logs directly to std::error, I think you may do the same)

Makes sense, thanks for the feedback!

[halfalicious]

Rebased (to get changelog) and updated changelog

[halfalicious]

Looks like there's a unit test that needs updating

[halfalicious]

This test is failing on osx but it's a test reliability issue since my changes don't touch the discovery part of the code:

510 - network/net/packetsWithChangedEndpointSuite/neighbours (Failed)

I'll open a new issue so we can track this.

[halfalicious]

Rebased to fix changelog