formatters/nancy: log correct errors

[wiliansilvazup]

What happened:
In PR #806 was create thread about errors returned from nancy tool, they are:
1º Output wrong;
2º Nancy return error with this log in debug mode nancy-output-error.txt but in end of the analysis the error in output is Can'ot possible convert 'C' to struct....

What you expected to happen:
Error about i not using GITHUB_TOKEN environment variable, but the error was other.

How to reproduce it (as minimally and precisely as possible):
Create multiple analysis in go examples folder in order to achieve github's rate-limit. And see this log only show in debug mode.

Anything else we need to know?:
You can use e2e test to validate if nancy is ok with change.