Error when parsing packages without an explicit package name

[mathsaey]

The following proto file, fails to compile for me:

syntax = "proto3";

message Test {
    string tst = 1;
}

It returns the following error:

** (FunctionClauseError) no function clause matching in String.split/3

    The following arguments were given to String.split/3:

        # 1
        nil

        # 2
        "."

        # 3
        []

    (elixir) lib/string.ex:383: String.split/3
    lib/protobuf/protoc/generator/util.ex:33: Protobuf.Protoc.Generator.Util.normalize_pkg_name/1
    lib/protobuf/protoc/generator/util.ex:11: Protobuf.Protoc.Generator.Util.attach_pkg/2
    lib/protobuf/protoc/generator/message.ex:22: Protobuf.Protoc.Generator.Message.parse_desc/2
    lib/protobuf/protoc/generator/message.ex:11: Protobuf.Protoc.Generator.Message.generate/2
    (elixir) lib/enum.ex:1294: Enum."-map/2-lists^map/1-0-"/2
    lib/protobuf/protoc/generator.ex:24: Protobuf.Protoc.Generator.generate_content/2
    lib/protobuf/protoc/generator.ex:11: Protobuf.Protoc.Generator.generate/2
--elixir_out: protoc-gen-elixir: Plugin failed with status code 1.

Adding package test; to the proto file fixes the problem.
However, since the --ccp_out generator seems to accept the original proto file, I don't think this behaviour is intended.

I don't have a lot of experience with protocol buffers, so forgive me if I'm doing something incredibly wrong here :).