Helidon exceptions are not propagated up through PbjProtocolHandler to the application via `onError`

[mattp-swirldslabs]

Description

An exception thrown in io.helidon.common.buffers.ReadOnlyArrayData invokes the onError() method in PbjProtocolHandler but that method does not signal an error to the application layer via Flow.Subscriber<? super Bytes> incoming. This prevents the application layer from taking action and cleaning up, etc.

Steps to reproduce

1. Put a breakpoint in the PbjProtocolHandler.onError() method on the running server:

   pbj/pbj-core/pbj-grpc-helidon/src/main/java/com/hedera/pbj/grpc/helidon/PbjProtocolHandler.java

   Lines 643 to 654 in a2e54fa

   	public void onError(@NonNull final Throwable throwable) {
   	if (throwable instanceof final GrpcException grpcException) {
   	new TrailerBuilder()
   	.grpcStatus(grpcException.status())
   	.statusMessage(grpcException.getMessage())
   	.send();
   	} else {
   	LOGGER.log(ERROR, "Failed to send response", throwable);
   	new TrailerBuilder().grpcStatus(GrpcStatus.INTERNAL).send();
   	}
   	close();
   	}

2. Force an exception and note that it's caught in the PbjProtocolHandler.onError() method.
3. Observe that this method never calls incoming.onError() or an equivalent to notify the application layer there was a problem.

Additional context

This is an example of how grpc.io handles the same exception:

Hedera network

No response

Version

v0.9.9

Operating system

macOS