gRPC clients fail silently (return null message) when services return an internal error

[DavideRossi]

Environment Details

• Helidon Version: 4.1.3
• Helidon MP
• JDK version: 21
• OS: linux

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Problem Description

When a gRCP service returns an error (with a gRCP code Internal, that is what happens when there is an internal error of some kind of the server side) Helidon's gRPC client returns a null message instead of raising en exception.
Notice that I did not try with other error codes.

The problem is fully reproducible.

Steps to reproduce

I set up this github repo to demonstrate the issue: https://github.com/DavideRossi/Wellness-gRPC/.
It's two gRPC services (temperature and humidity providers) with a REST API front end (that combines the aforementioned twos to produce a wellness score).
I didn't want to mess with a multi-modules project so I'm just producing three JARs from a common codebase by selectively removing other service, it's a ugly hack but it works.
In its current status it's working fine, but just because I added null-checks (see: https://github.com/DavideRossi/Wellness-gRPC/blob/f97e1bbfaecb0def6ff75be72b017f51[…]/main/java/it/unibo/ams/wellnessstream/TemperatureProvider.java).

Notice that a null return in place of raising an exception on errors is a problem, since the latter behavior is what most of the other framework components assume (as in the case of Fault Tolerance).