Remove code no control flow can reach, and the check that proves it

[jehrr]

playwright_scraper.py carried fifteen lines whose def line had been
lost. What remained -- a docstring and a try: return page.content() --
was indented at function level, so Python attached it to the end of
_mask_credentials, after that function's own return. It parses, it
imports, --help works, compileall passes and this suite was green,
because unreachable code is still valid code. Nothing called it, and
_content_when_settled directly below does the same job.

The same fifteen lines are in six repos of this family, byte for byte,
and have been since each one's first commit -- so this is inheritance
rather than authorship, the shape CLAUDE.md §16 describes.

The check added with it: a statement sitting after a
return/raise/break/continue in the SAME block. Deliberately narrow,
claiming nothing about reachability in general. The undefined-name walk
beside it cannot catch this class, and correctly so -- it pools every
binding in the file rather than tracking scopes, so page used inside
the dead block resolves against the page parameter of a real function
elsewhere in the module. That coarseness is the right trade for what
that check is for, which is why this is a separate check rather than a
tightening of it.

Measured across the eighteen repos of this family: six problems
reported, zero false positives. Verified by control -- appending a
function whose body is return 1 then x = 2 turns the suite red.

Co-Authored-By: Claude Opus 5 (1M context) noreply@anthropic.com

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