feat(asgi): no longer add NullHandler to the falcon logger

[vytas7]

We used to add a NullHandler() to falcon._logger which could be done according to the stdlib's docs,

"if you want to prevent your library's logged events being output to sys.stderr in the absence of logging configuration."

However, this has mostly resulted in confusion for people trying the ASGI flavour of the framework as HTTP 500 tracebacks may disappear completely, so the revised choice is NOT to prevent last resort logging to sys.stderr.

Fixes #2594.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (ecb7218) to head (d9709ed).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2595   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           64        64           
  Lines         7875      7874    -1     
  Branches      1078      1078           
=========================================
- Hits          7875      7874    -1     

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[CaselIT]

Makes sense to me.

I think it's fine to keep as part of a point release.

[vytas7]

I think it's fine to keep as part of a point release.

Aye, don't think it's an issue SemVer wise since it's an implementation detail of the private falcon._logger. We only specify that we use the falcon logger in rare cases where there is no other option, and that we don't configure anything behind the user's back (not any less true than before).