v0.52.0

Sixteen places in the package caught an exception and passed, each with
its reason in a comment beside the `pass` - the one thing a reader skips
and a gate cannot see. `swallow(why)` is a context manager that makes the
reason an argument: it sits on the line that swallows, it can be grepped,
and it is logged at debug with the traceback, so a silence that hides a
real defect can be heard by turning the logger up instead of by adding a
print. The workbench records what an unheard silence cost: a live pane
frozen on an old page for a whole session, the capture stopped, the only
sign a swallowed exception nobody could see.

A gate reads the package for the bare shape - `except Exception:` then,
comments aside, `pass` - and refuses it; it found three the grep that
listed the sixteen had missed. Three mutations, three killed: a bare pass
back with a good comment, a silence that stops logging, a silence that
re-raises.

One sentence of prose that described a session of eight browsers now
describes the two there are.