Fix issues spotted by codacy

[RainerKuemmerle]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 65.64%. Comparing base (0e0102b) to head (c33523b).
Report is 4 commits behind head on pymem.

Files with missing lines	Patch %	Lines
g2o/core/hyper_graph_action.cpp	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            pymem     #860      +/-   ##
==========================================
- Coverage   65.65%   65.64%   -0.01%     
==========================================
  Files         342      342              
  Lines       13410    13411       +1     
  Branches     1316     1316              
==========================================
  Hits         8804     8804              
- Misses       4214     4215       +1     
  Partials      392      392              

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