Feat: Improve error message for unconfigured computers

[ramirezfranciscof]

Fixes #4645

I added a check to the get_authinfo method of the computer class that improves on the error raised by the call to authinfos.AuthInfo.objects(...).get(...) when a (computer, user) couple is not found for the requested case. Also added a test that checks for the correct error raised, and also that the critical pieces of information are present in the error message.

[ramirezfranciscof]

@sphuber I still didn't add the check you wanted because I have a problem. In principle I would just need to call computer.get_authinfo( <SOME_USER> ) right after this line.

However, I'm not sure what user to provide or how to access it. In the case of the call inside the engine (the error shown in the issue #4645), the task was provided with the process as an input argument so it can get its underlying calcjob node and the user it belongs to. In the validator, however, I have no acces to the node (I only get the inputs and the context, but I couldn't find the class definition of the context to check if it has a reference to the calcjob node). Is there a way to either get that node or get the user from the profile that is currently loaded?

[codecov]

Codecov Report

Merging #4670 (87aff8e) into develop (75310e0) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #4670      +/-   ##
===========================================
+ Coverage    79.52%   79.52%   +0.01%     
===========================================
  Files          519      519              
  Lines        37083    37087       +4     
===========================================
+ Hits         29486    29491       +5     
+ Misses        7597     7596       -1     

Flag	Coverage Δ
django	74.24% <100.00%> (-0.01%)	⬇️
sqlalchemy	73.17% <100.00%> (+0.01%)	⬆️

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

Impacted Files	Coverage Δ
aiida/orm/computers.py	68.37% <100.00%> (+0.37%)	⬆️
aiida/orm/users.py	82.50% <0.00%> (+1.25%)	⬆️

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[ltalirz]

Also these test failures seem to have been caused by the Open SSH upgrade - please continue with review/approval

[giovannipizzi]

I have just only minor typo a dn one doubt where @sphuber might help, otherwise looks good to me

[giovannipizzi]

Good to go!