core: stdcm: avoid infinite loop in logger edge case

[eckter]

See comment for explanation. It triggered with the fuzzer, but I don't think it could have happened in real life conditions.

What made it annoying is that it's an infinite loop that isn't caught by the usual timeout, it would just lock a thread forever.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.56%. Comparing base (f4e0c84) to head (65aa2cc).
Report is 14 commits behind head on dev.

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@@            Coverage Diff             @@
##              dev   #10849      +/-   ##
==========================================
- Coverage   82.56%   82.56%   -0.01%     
==========================================
  Files        1084     1084              
  Lines      107256   107256              
  Branches      728      728              
==========================================
- Hits        88558    88557       -1     
- Misses      18657    18658       +1     
  Partials       41       41              

Flag	Coverage Δ
editoast	74.39% <ø> (-0.01%)	⬇️
front	90.47% <ø> (ø)
gateway	2.18% <ø> (ø)
osrdyne	3.28% <ø> (ø)
railjson_generator	87.58% <ø> (ø)
tests	87.91% <ø> (ø)

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