When connecting to Azure Event Grid MQTT Broker, existence of client certificates is not checked.

[mountaindude]

What version of Butler are you using?

9.4.0

What version of Node.js are you using? Not applicable if you use the standalone version of Butler.

No response

What command did you use to start Butler?

docker compose up

What operating system are you using?

macOS

What CPU architecture are you using?

x86_64

What Qlik Sense versions are you using?

2023-Aug

Describe the Bug

Butler uses client certificates when connecting to Event Grid MQTT broker.
There is however no check whether the certificate files really exist.

Expected Behavior

Verify that cert files exist. Log error if not, then exit with error code.

To Reproduce

No response