argo-events 1.9.6 broke Azure Event Hub EventSource

[ameszi]

Describe the bug
While experimenting with argo workflows and event hub triggers I ran across an issue with the 1.9.6 version of argo events.
My workflow is: upload blob -> event grid system topic set for blob creation -> publish to Event Hub namespace -> Argo EventSource set up for Event Hub source like in the examples.

The error is that I got a nil pointer exception in the event source pod, at the following line after a blob was uploaded: https://github.com/argoproj/argo-events/blob/v1.9.6/pkg/eventsources/sources/azureeventshub/start.go#L133

Publishing a plain text event manually via the Azure UI did NOT raise the error and the workflow was triggered in argo workflows.

Used version: argo-events helm chart v2.4.15 (v1.9.6 argo-events image)

To Reproduce
Steps to reproduce the behavior:

1. Set up an Azure Event Hub namespace with an Event Grid System Topic publishing blob events to the hub
2. Deploy Argo Events with helm chart v2.4.15
3. Deploy a default EventBus and an EventSource resource based on the argo-events Event Hub example
4. Upload a blob to the tracked blob storage
5. The argo events event source pod will crash with a panic: runtime error: invalid memory address or nil pointer dereference exception at the following line: https://github.com/argoproj/argo-events/blob/v1.9.6/pkg/eventsources/sources/azureeventshub/start.go#L133

Expected behavior
No crash happens.

Environment (please complete the following information):

• Kubernetes: v1.30.11
• Argo Events: v1.9.6
• Argo Events Helm Chart: v2.4.15

Additional context
Reverting back to helm chart v2.4.14 (1.9.5 argo-events) fixed the issue and the crash does not happen with the same setup.

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