core: add error on zero length simulations

[eckter]

We sometimes have 500 errors in prod because of this

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.93%. Comparing base (eeb8aa2) to head (c8a0b05).
Report is 12 commits behind head on dev.

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Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #10738      +/-   ##
==========================================
- Coverage   81.93%   81.93%   -0.01%     
==========================================
  Files        1078     1078              
  Lines      107555   107555              
  Branches      733      733              
==========================================
- Hits        88125    88123       -2     
- Misses      19391    19393       +2     
  Partials       39       39              

Flag	Coverage Δ
editoast	74.38% <ø> (-0.01%)	⬇️
front	89.42% <ø> (ø)
gateway	2.18% <ø> (ø)
osrdyne	3.28% <ø> (ø)
railjson_generator	87.50% <ø> (ø)
tests	88.14% <ø> (ø)

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[emersion]

Weird that we're still seeing this, editoast should avoid sending such requests now: #9931

I suppose more safety is always a good thing :P

[eckter]

Yeah we should investigate further, I'll create a different issue: #10762

But when it does happen, an exception is better than an assert error very far down the call stack