fix(worker): fix so that worker can be closed if Redis is down

[manast]

Fixes #372

[roggervalf]

Lgtm

[SrdjanCosicPrica]

Hi @manast @roggervalf

My project was on 5.1.0 before this, and after upgrading to 5.1.1, my jest tests started reporting

Jest did not exit one second after the test run has completed.

'This usually means that there are asynchronous operations that weren't stopped in your tests. Consider running Jest with `--detectOpenHandles` to troubleshoot this issue.

Adding --detectOpenHandles does not show anything so I believe I'm closing everything as expected. I'm not sure where the issue is since it worked fine before this patch

Edit:
It seems that, when running a couple of tests at the same time (with --runInBand), one worker gets

this.blockingConnection.status === 'initializing'

when closing. So the client becomes null and it does not call disconnect on it

[manast]

@SrdjanCosicPrica it would be great if you could isolate a test case where this happens so that we can reproduce it and fix it.

[SrdjanCosicPrica]

Ok I'll do my best to find some time to replicate it.
I solved my issue by adding a sleep of 10 ms Promise(resolve => setTimeout(resolve, 10)).

I'm using docker-compose during tests and my best guess is that the JS thread doesn't get enough time to establish a connection and mark it as ready before the test wants to complete. Adding the sleep gave enough time for the status to change.

[SrdjanCosicPrica]

Hey @manast I managed to reproduce it with minimal code that is close to how we are using it in the project where I discovered the issue.
https://github.com/SrdjanCosicPrica/bullmq-5.1.1-open-handles