Adding error message when fitting failed

[andrea-pasquale]

Closes #743 .

The following implementation does not require a marker file which I think is better.

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.
• Compatibility with Qibo modules (Please edit this section if the current pull request is not compatible with the following branches).
  • Qibo: master
  • Qibolab: main
  • Qibolab_platforms_qrc: main

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.86%. Comparing base (acef62e) to head (5d2e606).
Report is 2 commits behind head on fix_plot_chi2_protocols.

Additional details and impacted files

@@                     Coverage Diff                     @@
##           fix_plot_chi2_protocols     #745      +/-   ##
===========================================================
+ Coverage                    96.70%   96.86%   +0.15%     
===========================================================
  Files                          108      108              
  Lines                         7497     7490       -7     
===========================================================
+ Hits                          7250     7255       +5     
+ Misses                         247      235      -12     

Flag	Coverage Δ
unittests	96.86% <100.00%> (+0.15%)	⬆️

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

Files	Coverage Δ
src/qibocal/cli/report.py	100.00% <100.00%> (+16.66%)	⬆️

[alecandido]

I was unaware we already stored this information somewhere.

[andrea-pasquale]

I also had to think about it. We can separate the two cases since only with qq acquire Results is None while in the other case the instance of the class is created and all the dict attributes are filled only if the fit is successful.