Protobuf protocol: consider throwing exceptions in case of non Uint8Array arguments

[FZambia]

centrifuge-js expects Uint8Array for data in methods in Protobuf case. When passing non-Uint8Array data is skipped by serialization layer. I guess we can throw exceptions in such cases like we currently do in Python SDK.

For example, this is an incorrect RPC call in Protobuf protocol scenario:

centrifuge.rpc("method", {"input": "hello"})

The correct one is:

const rpcRequestData = {"input": "hello"};
const binaryData = new TextEncoder("utf-8").encode(JSON.stringify(rpcRequestData));
centrifuge.rpc("method", binaryData);

Since the usage is incorrect - throwing exception seems right.