Handle unsubscription safer while client closes

[gnought]

We're better not to inject a custom key close into one of argument in handleUnSubscribe fn. Malicious unsubscribe packet may break aedes unsubscribe logic.

[robertsLando]

LGTM

[mcollina]

Please add tests

[gnought]

@mcollina we already cover it in

aedes/test/meta.js

Lines 184 to 204 in 209efd0

	test('dont emit unsubscribe event on client close', function (t) {
	t.plan(3)
	const broker = aedes()
	t.tearDown(broker.close.bind(broker))
	const s = noError(connect(setup(broker), { clientId: 'abcde' }), t)
	broker.on('unsubscribe', function (unsubscriptions, client) {
	t.error('unsubscribe should not be emitted')
	})
	subscribe(t, s, 'hello', 0, function () {
	s.inStream.end({
	cmd: 'disconnect'
	})
	s.outStream.once('data', function (packet) {
	t.pass('unsubscribe completed')
	})
	})
	})

[robertsLando]

@gnought I think he means a test where a malicious packet with close prop is received

[robertsLando]

LGTM

[gnought]

ping @mcollina

[mcollina]

lgtm

[mcollina]

lgtm