Ensure chunk_size is properly set when chunking responses

[ml-evs]

Closes #1335.

The test added in 4352a85 does not trigger even without the fix, so still not entirely sure how to reliably trigger this bug.

[CasperWA]

Looks good to me, but as mentioned in #1335, it may not be an empty body that triggered the issue to begin with, but rather some form of response generation time out?
Difficult to test - however, it's always nice with some extra edge-cases tested, I suppose?

Thanks for the quick response and fix!

[codecov]

Codecov Report

Merging #1336 (3233ee0) into master (3387a8a) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1336      +/-   ##
==========================================
- Coverage   91.46%   91.45%   -0.01%     
==========================================
  Files          72       72              
  Lines        4368     4366       -2     
==========================================
- Hits         3995     3993       -2     
  Misses        373      373              

Flag	Coverage Δ
project	91.45% <100.00%> (-0.01%)	⬇️
validator	90.86% <100.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
optimade/server/middleware.py	94.87% <100.00%> (-0.07%)	⬇️

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[ml-evs]

Looks good to me, but as mentioned in #1335, it may not be an empty body that triggered the issue to begin with, but rather some form of response generation time out? Difficult to test - however, it's always nice with some extra edge-cases tested, I suppose?

Thanks for the quick response and fix!

Yeah, I've just played around with artificial pauses in the dummy endpoint but can't trigger it (and couldn't find a way within starlette to just drop the request). Do you want a hotfix release for this?

[CasperWA]

Yeah, I've just played around with artificial pauses in the dummy endpoint but can't trigger it (and couldn't find a way within starlette to just drop the request). Do you want a hotfix release for this?

Weird. It might be something different again then? At least the code base change is a good one either way.

If you're offering a hotfix release I'm game :)