Observability service getting empty errors in the callback function

[joaopgrassi]

While implementing the ObservabilityService interface to work with OpenTelemetry, I noticed that when errors happen during the several operations in cloudevents (client.go Send method), the callback in the observability service func(errOrResult error) is invoked with an empty error. Depending on the use case, developers would want to maybe mark the span created by the ObservabilityService as failed, but without the error result it's not possible to figure it out.

I started debugging to see why, and I found out that in several places the callback is called in a defer but before the error is actually collected. For example, here