[Quinnod345]

Passing a conforming custom logger whose empty record buffer makes it falsey to H2Configuration(logger=...) silently replaces it with DummyLogger. OutputLogger(file=...) has the same fallback for a valid falsey writable stream, so its output goes to stderr instead of the selected stream.

Select the defaults only when the argument is None. The new regressions cover an empty logger and a falsey writable stream with trace enabled and disabled. The existing default tests continue to pass.

Validation on CPython 3.13.11/macOS:

• The three new regressions fail on upstream a90a82d before the implementation changes.
• All 69 configuration tests and the complete 1,687-test suite pass after the change.
• The project-required 100% line and branch coverage, source Ruff checks and strict-bytes Mypy checks pass.

I maintain Ponder. Its review flagged this case; the regressions reproduce it.

[agammann]

Using an explicit is None fallback preserves a caller-supplied logger or output stream even when its truth value is false. The new tests exercise a falsey logger and a falsey file for both trace settings, and check that messages do not fall through to stderr. I reviewed the source and tests; I did not run them locally.