jsonizer this error

test.d

#! /usr/bin/env dub
/+ dub.sdl:
   dependency "jsonizer" version="~>0"
+/
import std.stdio;
import jsonizer;

struct ComponentList
{
	mixin JsonizeMe;

	enum Type
	{
		None,
		Whitelist,
		Blacklist
	}

	string component;
	string[] modules;
}

struct Settings
{
	mixin JsonizeMe;
	string path;

	this(in string path)
	{
		this.path = path.idup;
	}

	@jsonize
	{
		string realName;
		string userName;
		string nickName;
		long saveInterval;
		string[] commandPrefixes;
	}
	@jsonize(Jsonize.opt)
	{
		ComponentList.Type componentListType;
		ComponentList[] components;
	}
}

void main() {
    Settings x = Settings("hi");
    writeJSON!Settings("test.json", x);
}