Better error reporting

[Dmitry-Antipov]

Crashes are hard to find in current verkko log, also at some moment it would be nice to have more feedback like unoptimal parameters detected, or something went not how we expected but still was able to finish.
Definitely not top priority, just to keep in mind when thinking about refactoring

[skoren]

Added a simple post-processing script which will find the failed step and tail all the err files there, should hopefully at least capture the actual error though still noisy.