[core] attribute: warning on failure inside node callables

[fabiencastan]

When creating new nodes, it is difficult to debug if errors inside node's callables are ignored without any warning.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.50%. Comparing base (b21ca05) to head (af2940f).
⚠️ Report is 2 commits behind head on develop.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
meshroom/core/attribute.py	0.00%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2903      +/-   ##
===========================================
- Coverage    79.55%   79.50%   -0.05%     
===========================================
  Files           51       51              
  Lines         6974     6978       +4     
===========================================
  Hits          5548     5548              
- Misses        1426     1430       +4     

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