Deploying 0.3.0 to AB crashed the ProdDash server on restart:
TypeError: Cannot read properties of null (reading 'streams')
at server.js:273 req.on('close', () => state.streams.delete(res))
teardown() nulls `state` and then ends every open stream, which fires each
request's close handler — and the handler reached back through the `state`
it had just discarded. Any re-init with a browser connected would do it, so
saving admin config while a dashboard was open was enough to stop the whole
server, every module with it.
The stream handler now closes over this mount's Set rather than the module's
state: after teardown it deletes from a set nobody reads, which is harmless.
The same hazard existed anywhere a callback could outlive the mount — the
keepalive ping, a frame arriving from the listener mid-teardown, and the
/measure interval — and each is closed over or guarded now.
Reproduced first (open an SSE client, save config, watch it fall over) and
confirmed fixed against the same sequence.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
