Try read LuaValue

[ashtonmeuser]

Return the original ref when calling LuaValue.TryRead<LuaValue>. This is useful for generics where T may be LuaValue.

For example, the consider the following readonly LuaTable that reads from a backing IReadOnlyDictionary<TKey, TValue>. This works as is in all cases except when the key or value type is LuaValue itself.

public static LuaTable ReadOnlyDict<TKey, TValue>(IReadOnlyDictionary<TKey, TValue> backing)
{
    var proxy = new LuaTable();
    var metatable = new LuaTable();

    metatable[Metamethods.Index] = new LuaFunction("__index", (context, ct) =>
    {
        var keyValue = context.GetArgument(1);
        if (!keyValue.TryRead<TKey>(out var key) || !backing.TryGetValue(key, out var value))
            return new(context.Return(LuaValue.Nil));

        return new(context.Return(LuaValue.FromObject(value)));
    });

    metatable[Metamethods.NewIndex] = new LuaFunction("__newindex", (context, ct) =>
        throw new LuaRuntimeException(context.State, $"readonly table: cannot assign key '{context.GetArgument(1)}'"));

    metatable[Metamethods.Metatable] = "readonly";
    proxy.Metatable = metatable;

    return proxy;
}

P.S. I intend to make a PR with some of the collection wrappers I've created like the one above.