Fix race condition during reconnect sends UNSUB messages

[ajax-surovskyi-y]

This is a PR for #1320

Race condition during reconnect sends unsent UNSUB messages before CONNECT, triggering Authorization Violation errors

[scottf]

@ajax-surovskyi-y I'm inclined to accept this portion:

this.serverAuthErrors.clear(); // reset on successful connection

but not the other change.

I think what we need to do is figure out how to know that we are trying to transmit between disconnect and connect. Maybe a second check?

What would be useful is some repeatable test to be able to test this. If we have to use some sort of mock or simulation, that would be extremely helpful.

[ajax-surovskyi-y]

@scottf Thanks! I've updated the PR to include only the

this.serverAuthErrors.clear();

change.

I'll also try to come up with a repeatable test to reproduce the issue reliably.

Will follow up once I have something concrete.