Configuration Fix: Do not return nil as response

Response of StartMonitoring has no meaningful content. Therefore, we returned nil and nothing happened so far.

But now with Dashboard accesing it, the following error arose: "ERROR: [core] [Server #1 (closed)] grpc: server failed to encode response: rpc error: code = Internal desc = grpc: error while marshaling: proto: Marshal called with nil "

Its happening only now since so far, in the auto start mode, we directly executed StartMonitoring and not via gRPC.